2nd PUC

You can Download Chapter 1 Reproduction in Organisms Questions and Answers, 2nd PUC Biology Question Bank with Answers, Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.

Karnataka 2nd PUC Biology Question Bank Chapter 1 Reproduction in Organisms

2nd PUC Biology Reproduction in Organisms NCERT Text Book Questions and Answers

Question 1.
Why is reproduction essential for organisms?
Answer:
Reproduction is essential for organisms because it maintains the population of the young, adult, and aged persons and the continuity of the species generation by generation and introduces variation in the organisms which are essential for adaptation and existence of life on earth.

Question 2.
Which is a better mode of reproduction: sexual or asexual? Why?
Answer:
The better mode of reproduction is sexual reproduction. In sexual reproduction new characters and variations are produced that may have superior quality and better survival value than the parents.

Question 3.
Why is the offspring formed by asexual reproduction referred to as clones?
Answer:
Asexual reproduction results in the production of offsprings which are morphologically and genetically similar to one another and are also exact copies of their parents. Such a group of individuals are called clones.

Question 4.
Offsprings formed due to sexual reproduction have better chances of survival. Why ? is this statement always true?
Answer:
The progeny formed after asexual reproduction are exact copies of their parents. But in sexual reproduction the male and female gametes produced from different parents fuse to produce progeny, they may morphologically and genetically show minor variations from their parents.

Question 5.
How does the progeny formed from asexual reproduction differ from those formed by asexual reproduction?
Answer:
Asexual reproduction is a process where offsprings are produced by a single parent without the involvement of gamete formation. No meiosis occurs in asexual reproduction and the progeny are genetically similar to parents and they do not show any variation.

But in sexual reproduction, the individual is produced as a result of meiosis and gametic fusion, exhibit genetic variation and differ from either of the two parents as well as among themselves.

Question 6.
Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered a type of asexual reproduction?
Answer:

Asexual Reproduction	Sexual Reproduction
1.  Only single parent is involved in the production of new individuals. 2. All divisions are mitotic. 3. It doesn’t need the production of sex organs. 4. Newly formed individuals are identical to the parent. 5.   It doesn’t produce variability. 6.   It is rapid method of multiplication.	1. It involves two parents and offsprings arise from the fusion of two gametes each contributed by one parent. 2.  It undergoes meioses at one or another stage. 3. It requires the production of sex organs. 4.  Newly formed individ­uals show variations to their parents by new combination of characters. 5. It produce variability. 6.  It is a slower method of multiplication.

Vegetative reproduction is also considered as a type of asexual reproduction because

• The plants are the exact genetic copies of the parent.
• It is also a rapid method of multiplication.
• It does not produce plants of new varieties
  i.e., no variability is produced.

Question 7.
What is vegetative propagation? Give 2 suitable examples.
Answer:
Vegetative propagation in plants is a method of asexual reproduction in which the parts other than seeds are used as propagules. In fact, it is a method of propagation in those plants which have lost their capacity to produce, seeds or produce non-viable seeds (e.g., Banana, seedless Grapes, Rose, Pineapple, etc.) Among flowering plants, every part of the body, such as root, stem, leaf, or bud takes part in vegetative propagation. Modified tuberous roots can be propagated vegetatively when planted in soil (e.g., sweet potato).

Underground modified stems such as rhizomes (e.g., Ginger, Eichhornia or water hyacinth, etc.), corms (e.g., Colocasia, Banana, etc.), bulbs.(e.g., Garlic, onion, etc.), etc.

Question 8.
Define
(a) Juvenile phase
(b) Reproductive phase
(c) Senescent phase
Answer:
a. Juvenile phase: The adult phase of vegetative development, culminating in the production of reproductive structures.
b. Reproductive phase: The end of juvenile phase which marks the beginning of reproductive phase by producing flowers.
c. Senescent phase: It is the period between reproductive maturity and death of a plant.

Question 9.
Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?
Answer:
Higher organisms though show complexity yet reproduce sexually because it enables these organisms to survive during unfavorable conditions. It contributes to the evolution of the species by introducing variation in a population much more rapidly than asexual reproduction.

Question 10.
Explain why meioses and gametogenesis are always interlinked?
Answer:
In sexual reproducing organisms, meiosis occurs during gametogenesis to reduce the diploid number of chromosomes (2n) to haploid number of chromosomes (n) in the gametes. Thus, gametes are formed as a result of meiosis so that their chromosome number.

Question 11.
Identify each part in a flowering plant and write whether it is haploid (n) or diploid (2n)
Answer:

• Ovary – 2n
• Anther – 2n
• Egg – n
• Pollen – n
• Male gamete – n
• Zygote – 2n

Question 12.
Define external fertilization. Mention its disadvantage?
Answer:
Malm External fertilization occurs outside the body of the organisms in the water. It is also called external syngamy
e.g., most aquatic organisms (algae, fishes, and amphibians).

The major disadvantage of this type of fertilization is that the offsprings are not protected from the predators and their survival is threatened upto adulthood. Moreover, a large number of gametes are wasted.

Question 13.
Differentiate between a zoospore and a zygote.
Answer:

Zoospore	Zygote
Zoospores are the asexual reproductive structures produced by fungi and simple plants like algae. They are motile. They are haploid in nature.	Zygote is non-motile produced by the fusion of male and female gametes. A zygote is diploid in nature.

Question 14.
Differentiate between gametogenesis and embryogenesis.
Answer:

Gametogenesis	Embryogenesis
The process of formation of two types of games i.e., male and female gamates.	The process of development of an embryo from the zygote.

Question 15.
Describe the post-fertilization changes in a flower.
Answer:
After fertilization, the following changes occur in the flower:

• The petals, sepals, stamens, style and stigma are shed. In some cases the sepals remain persistent e.g., pea.
• The zygote developed into embryo.
• The fertilised ovule changes into seed.
• The wall of ovary produces wall of the fruit called pericarp.
• The ripened ovary with pericarp and seeds is called fruit.

Question 16.
What is a bisexual flower? Collect 5 bisexual flowers from your neighbourhood and write common and scientific names.
Answer:
A flower in which both the sex organs (androecium and gynoecium) are present is called a bisexual flower.
Common name Scientific name

• Mango flower – Mangefera indica
• Coconut – Cocos nucifera
• Pea – Pisum salivum
• Hibiscus – Hibiscus Rosa – sinenses
• Rose – rosa mulliflora
• Mustard – Brassica nigra

Question 17.
Why are offsprings of oviparous animals at great risk as compared to offspring of viviparous animals?
Answer:
In oviparous animals, the development of the zygote takes place outside the body of the female parent whereas, in viviparous animals, it takes place inside the body of the female. Because in oviparous animals, the fertilized eggs are laid in an open environment where they are not protected from predators. Thus their survival rate is very less as compared to offspring of viviparous animals.

Question 18.
Examine a few flowers of any cucurbit plant and try to identity the staminate and pistillate flowers. Do you know any other plant that bears unisexual flowers?
Answer:
In the staminate flowers, stamens are present, but pistils are absent. They cannot produce fruits. In the pistillate flower, pistils are present, but stamens are absent and produce fruits. The example of unisexual flowers is papaya and date palm.

2nd PUC Biology Reproduction in Organisms Additional Questions and Answers

2nd PUC Biology Reproduction in Organisms One Mark Questions 

Question 1.
Define life span.
Answer:
The period from birth to the natural death of an organism is the life span of that organism.

Question 2.
Define the term reproduction.
Answer:
It is a biological process in which an organism gives rise to young ones similar to itself.

Question 3.
Write the significance of reproduction.
Answer:
Reproduction enables the continuity of the race, generation after generation.

Question 4.
What is a clone?
Answer:
Morphologically and genetically similar individuals produced by a single parent. In this young ones is the exact copy of their parent.

Question 5.
What is binary fission?
Answer:
The type of asexual reproduction occurs in single-celled organisms. Where a cell divides into two halves and each rapidly grows into adults.

Question 6.
Name the type of reproduction that occurs in yeast.
Answer:
Bud formation.

Question 7.
Name the asexual reproduction structures produced by fungi.
Answer:
Zoospore.

Question 8.
Name the asexual reproductive structure produced by penicillium and sponge.
Answer:

• Penicillium – conidia
• Sponge – Gemmules

Question 9.
Name the aquatic weed to grow where there is standing water.
Answer:
Water hyacinth

Question 10.
Write the disadvantage of growing water hyacinth in water.
Answer:
It drains oxygen from water, which leads to the death of fishes.

Question 11.
What is the oestrus cycle?
Answer:
It is a heat period during which the sexual desire of the female animal is at its peak.

Question 12.
What is the menstrual cycle?
Answer:
Rhythmic series of changes in the sex organs that occur after 28 days.

Question 13.
Give the events that occur in sexual reproduction.
Answer:
Pre-fertilization, fertilization, and post-fertilization events.

Question 14.
Which are the 2 main Pre-fertilization events?
Answer:
Gametogenesis and gamete transfer.

Question 15.
What are isogametes?
Answer:
The male and female gametes of similar size (morphologically similar).

Question 16.
What are heterogametes?
Answer:
Morphologically dissimilar gametes are sperm and ovum.

Question 17.
What is a homothallic or monoecious plant?
Answer:
The plant in which both the sex organs are in the same flower.

Question 18.
What is a heterothallic or dioecious plant?
Answer:
The plant in which sex organs are in different flowers.

Question 19.
Differentiate between staminate and pistillate flower.
Answer:
The unisexual male flower is staminate. The unisexual female flower is pistillate.

Question 20.
What are hermaphrodite ?
Answer:
The animals in which both the sex organs are there in the same body are called hermaphrodites.

Question 21.
Name the type of division occurs in meiocytes (gamete mother cells).
Answer:
meiotic division

Question 22.
Define Parthenogenesis.
Answer:
Development of an egg without the participation of sperm.

Question 23.
Define syngamy?
Answer:
The fusion of gametes results in the formation of a zygote.

2nd PUC Biology Reproduction in Organisms Two Marks Questions

Question 1.
Find the odd one and give reason
a. Rhizome, sucker, gemmule, offset.
b. Zoospore, buds, conidia, tuber
Answer:
a. Gemmule is the asexual reproductive structure of sponges, all others are vegetative propagules of angiosperms.
b. Tuber is a vegetative propagule, all others are asexual reproductive structures of smaller organisms.

Question 2.
Explain parthenogenesis with examples.
Answer:
The process of development of a new organism from a female gamete without fertilization is called parthenogenesis. For example, Rotifers, honey bees, turkey (birds).

Question 3.
Meiosis doesn’t take place in haploid cells. Why?
Answer:
In haploid cells, meiosis doesn’t take place as there is no homologous chromosome. Therefore only mitotic division takes place.

Question 4.
Distinguish homogametic and heterogametes.
Answer:
In some algae, the two gametes produced during sexual reproduction are so similar in appearance and they cannot be differentiated. Such gametes are homogametic. In the majority of sexually reproducing organisms, the gametes produced are of two morphologically distinct types. Such gametes are heterogametes.

2nd PUC Biology Reproduction in Organisms Three Marks Questions

Question 1.
Write the disadvantages of external fertilization over internal fertilization.
Answer:

• For external fertilization, the medium is required for the gamete transfer i.e. water.
• A large number of male gametes have to released in water medium to enhance the chances of syngamy.
• The offsprings are extremely vulnerable to predators threatening their survival up to adulthood.

You can Download Chapter 4 Reproductive Health Questions and Answers, 2nd PUC Biology Question Bank with Answers, Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.

Karnataka 2nd PUC Biology Question Bank Chapter 4 Reproductive Health

2nd PUC Biology Reproductive Health NCERT Text Book Questions and Answers

Question 1.
What do you think is the significance of reproductive health in a society?
Answer:
The significance of reproductive health in a society is:

• Creating awareness among people about various reproduction-related aspects.
• Providing facilities and support for building up a reproductively healthy society.
• Various health centres ensure the safe delivery of infant and postnatal care.
• Immunization of infants against various diseases.
• Various family planning techniques and preventive methods against sexually transmitted diseases.
• Creating awareness about the consequences of uncontrolled population growth and social evils (sex abuses and sex-related crimes, use of drugs, tobacco, and alcohol, etc.) among young people.
• Introduction of sex education in schools.

Question 2.
Suggest the aspects of reproductive health which need to be given special attention in the present scenario.
Answer:
Increased health facilities along with better living conditions had an explosive impact on the growth of the population. In this light, we must take care of the population explosion and try to minimise the birth rate. Otherwise, we will face an absolute scarcity of basic requirements.

Question 3.
Is sex education necessary in schools? Why?
Answer:
Sex education is necessary in schools in order to give the right information to young minds about reproductive organs, adolescence related changes, safe sexual practices, sexually transmitted diseases, etc. All this knowledge will save them from myths and misconceptions about sex-related aspects and also help them to lead a reproductively healthy life later in the future.

Question 4.
Do you think that reproductive health in our country has improved in the past 50 years? If yes, mention some such areas of improvement.
Answer:
Yes. Some such areas of improvement are the following.

• Made awareness among the people about reproduction-related aspects through audiovisual and printed media by governmental as well as non-governmental agencies.
• Motivated smaller families by using various contraceptive methods.
• Incentives given to couples with small families.
• Specialized health care units (infertility clinics etc.) could help couples suffering from infertility through assisted reproductive technologies (ART).

Question 5.
What are the suggested reasons for the population explosion?
Answer:
The reasons for the population explosion are:

• Decline in death rate.
• Decline in maternal mortality rate.
• Decline in infant mortality rate (IMR).
• Increase in the number of people in the reproductive age.
• Advancement in technology avoiding hunger death.

Question 6.
Is the use of contraceptives justified? Give reasons.
Answer:
An ideal contraceptive should be user-friendly, easily available, effective, and reversible with no or least side effects. It should also not interfere with the sexual drive, desire, and the sexual act of the user. So it is advisable to use contraceptives to check the population explosion.

Question 7.
Removal of gonads can not be considered as a contraceptive option, why?
Answer:
Devices or other agents that are used in artificial methods of preventing pregnancy are known as contraceptives. An ideal contraceptive should be user-friendly, easily available, effective with least or no side effects, should not interfere with the sexual drive, desire, or the sexual act of the user. It should also be reversible. But the removal of gonads is an irreversible process and will lead to infertility in both males and females. Moreover, gonads also produce hormones which are essential for the body. Thus, the removal of gonads cannot be considered as a contraceptive option.

Question 8.
Amniocentesis for sex determination is banned in our country. Is this ban necessary? Comment.
Answer:
Amniocentesis is a prenatal diagnostic technique used to determine chromosome abnormalities of the foetus. If the embryo contains any hereditary defects, the parents may be advised for abortion. But nowadays this technique is misused for determining fetal sex. So the statutory ban on amniocentesis is necessary. Otherwise, it will lead to female foeticides and sexual imbalance.

Question 9.
Suggest some method to assist infertile couples to have children.
Answer:
Some methods to assist infertile couples to have children are:

• Test tube babies – In this the fusion of ovum and sperm is done outside the body of a woman to form a zygote which is allowed to divide to form embryo. This embryo is then implanted in the uterus where it develops into a foetus.
• Artificial insemination Technique (AIT)- In this, the semen collected either from a husband or a healthy donor is artificially introduced either into the vagina or into the uterus (IUI – Intra Uterine Insemination) of the female.
• Gamete intra Fallopian transfer (GIFT)- This method is used in females who cannot produce ova but can provide a suitable environment for fertilisation and further development of embryos in the oviducts. In such cases, ovum from the donor female is introduced into the Fallopian tube of such females. Such women then accept sperms from their husbands during copulation.
• Intracytoplasmic sperm injection (ICSI)- This is another specialized technique to form an embryo in the laboratory in which a sperm is directly injected into the ovum placed in a nutrient broth. The zygote or early embryo is later transferred to the Fallopian tube of the woman by ZIFT.

Question 10.
What are the measures one has to take to prevent STDs?
Answer:

• Avoid sex with unknown/multiple partners.
• Always use condoms.
• Avoid early or late marriages.
• Early detection and complete cure in case of doubt.

Question 11.
Correct the following statements.

1. Surgical methods of contraception prevent gamete formation.
2. All sexually transmitted diseases are completely curable.
3. Oral pills are very popular contraceptives among rural women.
4. In E. T. techniques, embryos are always transferred into the uterus.

Answer:

1. Surgical methods of contraception prevent gamete transport and hence prevent fertilisation.
2. Only a few sexually transmitted diseases are completely curable if detected early and treated properly.
3. Oral pills are very popular contraceptives among educated urban women.
4. In E.T techniques, 8 celled embryos are transferred into Fallopian tubes and more than 8 celled embryos are transferred into the uterus.

Question 12.
Correct the following statements.
a. Surgical methods of contraception prevent gamete formation.
b. All sexually transmitted diseases are completely curable.
c. Oral pills are very popular contraceptives among rural women.
d. In E. T. techniques, embryos are always transferred into the uterus.
Answer:
a. Surgical methods of contraception prevent unwanted pregnancy.
b. Except for hepatitis B, genital herpes, and HIV, other diseases are completely curable if detected early and treated properly.
c. Oral pills are very popular contraceptives among women.
d. In E.T. techniques, embryos formed by IVF (in vitro fertilisation) are transferred into the uterus.

2nd PUC Biology Reproductive Health Additional Questions and Answers

2nd PUC Biology Reproductive Health One Mark Questions 

Question 1.
What do you understand by the term “Reproductive health”?
Answer:
The term reproductive health refers to healthy reproductive organs and then normal functioning.

Question 2.
What is reproductive health according to the World Health Organisation ?
Answer:
According to the World Health Organisation, reproductive health means total well-being in physical, emotional, behavioural, and social aspects of reproduction.

Question 3.
Expand MMR and IMR.
Answer:

• MMR – Maternal Mortality Rate.
• IMR – Infant Mortality Rate.

Question 4.
Write one reason for the ban on amniocentesis.
Answer:
Amniocentesis is used to find out the sex of the foetus and it leads to female foeticide
i. e., killing of female foetus.

Question 5.
Mention any 2 probable reasons for rapid rise of population in our country from about 350 millions at the time of independence to about 1 billion by the year 2000.
Answer:
The reasons are

• Decline in death rate
• Decline in maternal mortality rate
• Decline in IMR.

Question 6.
Which of the following represents an increase or decrease in population
Answer:

• Decrease in population : Mortality and emigration.
• Increase hi population: Immigration and Natality.

Question 7.
Give 2 important measures taken by the government to tackle the problem of population explosion.
Answer:

• Statutory rising of marriageable age of the female to 18 years and that of the male 21 years.
• Incentives given to the couples with micro family.

Question 8.
Expand MTP and STD.
Answer:

• MTP – Medical termination of pregnancy.
• STD – Sexually transmitted disease.

Question 9.
Name 2 viral STDs that are incurable.
Answer:
Genital herpes, AIDS.

Question 10.
What are Assisted reproduction technologies. [ART]? [Delhi 2008]
Answer:
ART are the special techniques to help the infertile couples to produce children.

Question 11.
What are the different ways in which progesterone or progesterone – estrogen combination can be taken for contraception?
Answer:

• Oral pills
• Injections
• Implants.

Question 12.
Write the other 2 names given for STDs.
Answer:
Venereal Diseases (VDs) and Reproductive tract infections (RTI).

Question 13.
Name 2 STDs that can be transmitted by sharing injection needles or surgical instruments.
Answer:
Hepatitis – B, AIDS.

Question 14.
What is In vitro fertilization?
Answer:
It involves fertilization of the ovum outside the body followed by the transfer of the embryo inside the uterus.

Question 15.
Expand

• IVF
• ZIFT
• IUT
• GIFT
• ICSI
• AI
• IUI
• ART

Answer:

• IVF – In Vitro Fertilization
• ZIFT – Zygote intra fallopian transfer
• IUT – Intra Uterine Transfer
• GIFT – Gamete intra fallopian transfer.
• ICSI – Intra cytoplasmic Sperm Injection.
• AI – Artificial insemination.
• IUI – Intra uterine Insemination
• ART – Assisted Reproductive Technologies.

Question 16.
After a successful invitro fertilization, the fertile egg begins to divide. Where is this egg transferred before it reaches the 8 cells stage and What is this technique named ?
Answer:
It will be (egg) transferred into the fallopian tube; the technique is called zygote intra fallopian transfer (ZIFT).

2nd PUC Biology Reproductive Health Two Marks Questions

Question 1.
Amniocentesis for sex determination is banned in our country. Is this ban necessary? Comment. [CBSE – 2006]
Answer:
Since the amniocentesis is misused for female foeticide, the ban is necessary. But by banning this, its advantage of finding out any chromosomal disorders and / or metabolic disorders of the foetus is lost. So, it should be legalized with some strict conditions to avoid its misuse.

Question 2.
Why is hormone releasing IUD considered a good contraceptive to space children? [CBSE – 2008]
Answer:
Hormone releasing IUDs

• Make the uterus unsuitable for implantation.
• Make the cervix hostile to sperms.
• Increase the phagocytosis of sperm within the uterus.

Question 3.
Differentiate between coitus interruptus and lactational amenorrhea.
Answer:
Coitus interruptus: In this, the male partner withdraws his penis just before ejaculation.
Lactational amenorrhea: During intense lactation following delivery, the menstrual cycle does not occur. Therefore as long as the mother breastfeeds the child, the chance of conception is almost nil. This is to be effective only upto six months following delivery.

Question 4.
How do pills act as contraceptives in human females ?
OR
Name the hormonal composition of the oral contraceptive used by human females. Explain how does it act as a contraceptive.
Answer:

• Pills contain progesterone or
• progesterone-estrogen combination.
• They inhibit ovulation
• They alter the quality of cervical mucus and retard the entry of sperms into cervix.

Question 5.
How are pills more effective than other contraceptives?
Answer:
The pills are mainly a combination of hormones. These are to be taken daily for a period of 21 days starting within the first five days of the menstrual cycle. After a gap of 7 days repeat the same pattern till the female desires to prevent pregnancy. This is effective because of lesser side effects.

Question 6.
Family planning techniques are not adopted by all in our country. Why?
Answer:
Because

• Religious belief
• People are not fully aware of the method.
• Emotional and social factors
• Fear of some of the ill effects.

Question 7.
In India, there are thousands of couples without children. Is adoption a better method for them?
Answer:
Yes. In India, we have a lot of orphaned and destitute children, and our laws permit legal adoption. Even then the couples go for their ultimate ambition of parenthood.

2nd PUC Biology Reproductive Health Three/Five Marks Questions

Question 1.
Give any six reproduction related issues.
Answer:

• Pregnancy
• Child birth / Parturition
• STDs
• Abortions
• Menstrual problem
• Infertility
• conceptive methods.

Question 2.
How lUDs prevent pregnancy?
Answer:

• IUDs increase phagocytosis of sperms within the uterus.
• The Cu ions released by IUDs suppress the term motility and their fertilizing capacity.
• The hormone releasing IUDs make the uterus unsuitable for implantation and cervix hostile to the sperms.

Question 3.
Represent diagrammatically the sterilization method, vasectomy in male reproductive system and tubectomy in female reproductive system.
Answer:

Question 4.
A couple having no child approaches a doctor. The lady failed to conceive due to two previous unexpected abortions. The doctor proposed a hormone treatment.
a. Name the hormone that would be useful for this treatment
b. Name the organs which secrete these hormones in females
c. List out the physiological functions of this hormone
Answer:
a. Progesterone
b. Ovary and Placenta
c. i. Implantation
ii. Maintains pregnancy
iii. Prepares mammary glands for lactation
iv. Regulates oogenesis
v. Inhibits ovulation

You can Download Chapter 3 Human Reproduction Questions and Answers, 2nd PUC Biology Question Bank with Answers, Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.

Karnataka 2nd PUC Biology Question Bank Chapter 3 Human Reproduction

2nd PUC Biology Human Reproduction NCERT Text Book Questions and Answers

Question 1.
Fill in the Blanks:

1. Humans reproduce …………………….. (asexually/ sexually)
2. Humans are …………………….. (oviparous, viviparous, ovoviviparous)
3. Fertilization is …………………….. in humans, (external/internal)
4. Male and female gametes are …………………….. (diploid/haploid)
5. Zygote is …………………….. (diploid / haploid)
6. The process of release of ovum from a mature follicle is called ……………………..
7. Ovulation is induced by a hormone called ……………………..
8. The fusion of male and female gametes is called ……………………..
9. Fertilisation takes place in ……………………..
10. The zygote divides to form …………………….. which is implanted in the uterus.
11. The structure which provides a vascular connection between fetus and uterus is called ……………………..

Answer:

1. Sexually
2. Viviparous
3. Internal
4. Haploid
5. Diploid
6. Ovulation
7. LH and FSH
8. Fertilisation
9. Fallopian tube
10. Embryo
11. Placenta.

Question 2.
Draw a labelled diagram of male reproductive system.
Answer:

Question 3.
Draw a labelled diagram of the female reproductive system.
Answer:

Question 4.
Write two major functions each of testis and ovary.
Answer:
Testes – Testes are the primary sexual organs in males. Two major functions of testes are

• Testosterone production from Leydig cells.
• Production of sperm cells in seminiferous tubules.

Ovary – Ovaries are the primary female sex organs. Two main functions of ovaries are

• Productions of female germ cells called eggs or oocytes.
• Production of hormones – estrogens & progesterone which affect many of the female secondary sexual characters & reproductive functions.

Question 5.
Describe the structure of a seminiferous tubule.
Answer:
The testis has about 250 compartments (Testicular lobules) which contain 1-3 highly coiled seminiferous tubules. Each tubule is lined by 2 types of cells. Male germ cells (immature) (spermatogonia) and Sertoli cells.

Male germ cells form sperms by meiosis and Sertoli cells provide nutrition to these germ cells. Male germ cells and Sertoli cells together form germinal epithelium. A seminiferous tubule is covered outside by a basement membrane.

Question 6.
What is spermatogenesis? Describe the process of spermatogenesis.
Answer:
Spermatogenesis is the production of sperms (n) by immature male germ cells (2n) at puberty inside the testis.

Hormonal role in spermatogenesis:
Spermatogenesis starts due to an increase in the secretion of GnRH (Gonadotropin-Releasing Hormone) by the hypothalamus. GnRH acts on the Anterior pituitary gland and stimulates the secretion of 2 gonadotropins – LH (Luteinizing Hormone) or ICSH (Interstitial Cell Stimulating Hormone) and FSH (Follicle Stimulating Hormone).

LH acts on Leydig cells for secreting testosterone and other androgens inturn stimulates process of spermatogenesis. FSH acts on sertoli cells which secretes some factors useful in spermiogenesis. Sertoli cells secrete inhebin that suppresses FSH synthesis.

It is the production of haploid spermatozoa from diploid spermatogonia inside the testis at puberty. At puberty, Spermatogonium undergoes mitosis forms 2 spermatogonia A and B. Both A and B are diploid with 46 chromosomes each.
A: Function as mother spermatogonia.
B: Grow in size to function as primary spermatocytes.
They then undergo meiosis to form 2 haploid cells called secondary spermatocytes (23 chromosomes). They then undergo 2nd meiotic division forming 4 haploid spermatids. These spermatids are transferred into spermatozoa (sperms) by spermiogenesis. After spermiogeneses, sperm heads become embedded into Sertoli cells and are released from seminiferous tubules by a process called spermiation.

Question 7.
Name hormones involved in the regulation of spermatogenesis.
Answer:
After sexual maturity, spermatogenesis starts due to the secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus of brain. GnRH acts on pituitary gland and stimulates secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH). LH induce the Leydig’s cells of the testis to produce male sex hormones called androgens. High level of androgens stimulate the process of spermatogenesis. FSH acts on the Sertoli cells and stimulates secretion of some factors which help in the process of spermiogenesis.

Question 8.
Define spermiogenesis and spermiation.
Answer:
Spermiogenesis is the final stage of spermatogenesis in which there is the maturation of spermatids into mature, motile spermatozoa. Spermiation is the release of mature spermatozoa from the surface of the Sertoli cell into the lumen of the seminiferous tubules

Question 9.
Draw a labelled diagram of sperm.
Answer:

Question 10.
What are the major components of seminal plasma?
Answer:
Seminal plasma consists of secretions of seminal vesicles, prostate gland and bulbourethral glands. It contains fructose, prostaglandins, citrate, inositol, dotting proteins, (secretions of seminal vesicles), calcium, phosphate, bicarbonate, enzymes, prostaglandins (secretions of prostate gland) and mucus (secretion of bulbourethral glands).

Question 11.
What are the major functions of male accessory ducts and glands?
Answer:
Major functions of male-accessory ducts are

• Aid in sperm transport.
• Temporary storage of spermatozoa.

Male accessory glands secretions constitute the seminal plasma. These secretions are rich in fructose, ascorbic acid, citrate, calcium, certain enzymes and prostaglandins. These secretions nourish and activate the spermatozoa to swim.

Question 12.
What is oogenesis? Give a brief action of oogenesis.
Answer:
Process of formation, development and maturation of haploid ovum or female gamete from diploid germinal cell of the ovary.
Cells of the germinal epithelium of ovary undergo repeated mitotic divisions to form diploid Oogonia or gamete mother cells. They are formed in the fetal ovary in large number by mitotic division from primary oocyte.

The primary oocyte enlarges and matures by taking food from the surrounding follicle cells. The mature primary oocyte undergoes its first meiotic division. It is an unequal division resulting in the formation of a large haploid secondary oocyte and a tiny first polar body or polocyte. The secondary oocyte remains bulk of the nutrient ride cytoplasm of the primary oocyte. The secondary oocyte undergoes second meiotic division which doesn’t proceed beyond metaphase until a sperm enters it. Ovulation occurs at this stage and the secondary oocyte is transferred to the fallopian tube.

Question 13.
Draw a labelled diagram of the section through the ovary.
Answer:

Question 14.
Draw a labelled diagram of the Graafian follicle.
Answer:

Question 15.
Draw diagramatic representation of various events during menstrual cycle.
Answer:

Question 16.
Name the functions of the following.

1. Corpus luteum
2. Endometrium
3. Acrosome
4. Sperm tail
5. Fimbriae

Answer:

1. Corpus luteum: It secretes the hormone progesterone, which prepares the uterus for implantation. If implantation fails the corpus luteum becomes inactive and degenerates. If an embryo gets implanted, the corpus luteum continues to secrete progesterone until the fourth month of pregnancy, after that the placenta takes over this function.
2. Endometrium: It is the mucous membrane lining the uterus, which becomes progressively thicker and more glandular and has an increased blood supply in the latter part of the menstrual cycle. This prepares the endometrium for implantation of the embryo, but if this does not occur much of the endometrium breaks down and is lost in menstruation. If pregnancy is established the endometrium becomes the decidua, which is shed after birth.
3. Acrosome: A membranous sac at or near the front of a sperm that assists in penetration of the egg. The acrosome contains enzymes, which are released when the sperm contacts the egg prior to fertilisation. The enzymes break down the outer layers of the egg to permit entry of
   the sperm.
4. Sperm tail: The tail is a fine vibrating posterior portion of the sperm which helps in swimming. This ability to swim (called motility) is essential for male fertility as the sperm has to swim up the vaginal canal, cervix and cervical canal to reach to the ovtim.
5. Fimbriae: They help in the collection of ovum after ovulation.

Question 17.
Identify True / False statements. Correct each false statement to make it true,

1. Androgens are produced by Sertoli cells.
2. Spermatozoa get nutrition from Sertoli cells.
3. Leydig cells are found in ovary
4. Leydig cells synthesize androgens
5. Oogenesis occurs in corpus luteum.
6. Menstrual cycle ceases during pregnancy.
7. Presence or absence of hymen is not a reliable indicator of virginity or sexual experience.

Answer:

1. False. Androgens are produced by Leydig cells.
2. True
3. False. It is found in the testis.
4. True
5. False. Oogenesis takes place in the ovary.
6. True
7. True

Question 18.
What is the menstrual cycle? Which hormone regulates the menstrual cycle?
Answer:
The reproductive cycle in the female primates is called the menstrual cycle. The uterus linings become thick and spongy to receive fertilised egg. If the egg is not fertilized, this lining is not needed any longer so, it slowly breaks and comes out through vagina along with blood and mucous. This is called menstruation. It is repeated at an average interval of about 28/29 days.
Following hormones regulate this cycle:

• Gonadotropin
• estrogen
• Luteinizing hormone
• Follicular stimulating hormone
• Progesterone.

Question 19.
What is parturition? Which hormones are involved in the induction of parturition?
Answer:
The average duration of human pregnancy is about 9 months which is called gestation period. Vigorous contraction of the uterus at the end of pregnancy causes expulsion/delivery of the foetus. This process of delivery of the foetus is called parturition. It is induced by hormone oxytocin which acts on the uterine muscle and causes stronger uterine contractions.

Question 20.
In our society women are blamed for giving birth to daughters. Can you explain why this is not correct?
Answer:
Sex chromosome pattern in females is xx, i.e., both the gametes are with ‘X’ chromosomes. In males, sex chromosome is X Y i.e., one gamete with ‘X’ chromosome and other gametes with ‘Y’. So 50% sperms carry ‘X’ and 50% carry ‘Y’. A female child is producing when the sperm with ‘X’ chromosome fertilizes egg with ‘X’ chromosome. A male child is producing when sperm with ‘Y’ chromosome fertilizes egg with ‘X’ chromosome. Therefore sex of a baby depends on the father, not on the mother.

Question 21.
(a) How many egg are released by a human ovary in a month?
(b) How many eggs do you think would have been released if the mother gave birth to identical twins?
(c) Would your answer change if the twins born were fraternal?
Answer:
(a) Only one egg is released by a human (female) ovary in a month.
(b) Only one egg is released if the mother gave birth to identical twins.
(c) Yes, two or more eggs are released in case fraternal twins are born.

Question 22.
How many eggs do you think were released by the ovary of a female dog, which gave birth to 6 puppies?
Answer:
six eggs

2nd PUC Biology Human Reproduction Additional Questions and Answers

2nd PUC Biology Human Reproduction One Mark Questions

Question 1.
Where are sperm produced in the testis?
Answer:
In the seminiferous tubules of testis.

Question 2.
What is the role of placenta?
Answer:
Provide nutrition to the developing embryo.

Question 3.
What is the function of amniotic fluid?
Answer:
Protects foetus from shock.

Question 4.
Name the germ layer from which gonad develops.
Answer:
Mesoderm

Question 5.
Name the sperm lysin ? Which organelle secretes it ?
Answer:
Hyaluronidase; Acrosome.

Question 6.
Define gametogenesis.
Answer:
The process of formation of male and female gamete in the gonads is called gametogenesis.

Question 7.
The spermatogonia of an animal contains 32 chromosomes. What will be the number of chromosomes in its
(a) secondary spermatocyte
(b) spermatids respectively
Answer:
(a) Secondary spermatocyte – 16 chromosome
(b) spermatids -16 chromosome

Question 8.
Name the structure formed from Graafian follicle after ovule?
Answer:
Corpus luteum

Question 9.
Name the hormone secreted by corpusluteum.
Answer:
Progesterone.

Question 10.
Define spermiogenesis ? Where does it occur ?
Answer:
The process of the transformation of spermatids into spermatozoa is called spermiogenesis. It occurs in the seminiferous tubules of testis.

Question 11.
Why middle piece of the sperm called power house of the sperm ?
Answer:
Middle piece contains numerous mitochondria which produce energy for sperm movement.

Question 12.
Define Oogenesis.
Answer:
The process of formation of mature female gametes.

Question 13.
Name the fluid filled space in the tertiary follicle.
Answer:
Antrum

Question 14.
What is the significance of secondary oocyte retaining the bulk of nutrient rich cytoplasm of the primary oocyte ?
Answer:
These reserve food materials nourish the embryo till implantation.

Question 15.
When do the levels of FSH and LH reach the maximum in the menstrual cycle ?
Answer:
The peak level of FSH and LH is reached in the middle of (14th day) menstrual cycle.

Question 16.
Define implantation?
Answer:
Implantation is the process in which the mammalian embryo (blastocyst) becomes attached to the endometriosis of the uterus.

Question 17.
What are the stem cells in human embryo?
Answer:
Stem cells are those cells in the inner mass of the blastocyst, which have the potency to give rise to all tissues and organs.

Question 18.
What is colostrum ? How does it provide initial protection against diseases to new born infants. Give reason.
Answer:
The milk produced during initial few days of lactation is called colostrum. It consists of several antibodies like IgA etc. which are essential for the development of resistance in new born babies.

2nd PUC Biology Human Reproduction Two Marks Questions

Question 1.
Name 2 types of cells present in the inner lining of seminiferous tubules. What are their functions?
Answer:
Two types of cells in the inner lining of seminiferous tubule are

• Spermatogonia : Spermatogonia produces male gamete called spermatozoa.
• Sertoli cells : Sertoli cells provide nutrition to the developing spermatozoans.

Question 2.
Where are Leydig cells present? What is their role in reproduction?
Answer:

• Ley dig cells are located in the interstitial space (space between the seminiferous tubule) in the testis.
• They secrete testicular hormones called androgens, mainly testosterone, this hormone regulates spermatogenesis.

Question 3.
Differentiate between vasa efferentia and vas deferens.
Answer:

• Vasa efferentia are the ducts that leave the testis to open into epididymis. These are located inside the testis and are extra abdominal and do not receive the ducts of any glands.
• Vas deferens is the duct continues from epididymis. This ascends into the abdominal cavity. It receives the ducts of seminal vesicle.

Question 4.
Where are fimbriae present in a human female reproductive system ? Give their function.
Answer:
Fimbriae are present in the free edges of the infundibulum of the fallopian tube. Then help in the easy capture of ova during ovulation.

Question 5.
Differentiate between endometrium and myometrium.
Answer:

• Endometrium is the innermost glandular layer that lines the uterine cavity. It undergoes cylindrical changes during menstrual cycle. Implantation occurs in this layer.
• Myometrium is the middle thick layer of smooth muscles of the uterine wall. It doesn’t undergo any changes during menstrual cycle. It is responsible for the uterine movement.

Question 6.
Write the importance of inguinal canal in human reproductive system.
Answer:
In males, the testis is formed in the abdomen close to kidneys. Soon after birth or at the 8th month of pregnancy, the testis descend into the scrotal sacs through a canal known as inguinal canal. If it is not present, the testis cannot reach to the scrotal sac.

Question 7.
Mention the sites of action of the hormones – GnRH and FSH, during spermatogenesis in human males. Give one function of each of the hormones.
Answer:
GnRH acts on anterior pituitary and FSH acts on Sertoli cells of seminiferous tubules.
GnRH stimulates the release of two gonadotropin – Follicle-stimulating hormone and luteinizing hormone (LH) from the anterior pituitary. FSH stimulates the Sertoli cells to secrete some factors necessary for spermiogenesis.

Question 8.
Name the parts formed in the human embryo after
a. one-month
b. second-month
c. third-month
d. fifth month
Answer:
a. Heart
b. Limbs and digits
c. Limbs and genital organs
d. Appearance of hair on head

Question 9.
Given below is the diagram of the sectional view of human ovum just after ovulation.

Mention the site of fertilization in the fallopian tube of a human female where the ovum and sperm meet.
Answer:
Ampullary – Isthmus Junction.

Question 10.
How it blastula/blastocyte differ from Morula?

Blastocyte	Morula
(a) It is a hollow sphere of 32 or more cells formed by the rearrangement of blastomeres. (b) Zona pellucida disintegrates with the enlargement of the blastocoel	(a) It is a solid sphere of 8-16 cells blastomeres by cleavage of zygote. (b)  Zona pellucida is intact.

Question 11.
What are chroionic villi ? What is their fate?
Answer:
The finger-like projections of the trophoblast produced after implantation are called chronic villi. Chroionic villi and uterine tissue become interdigitated with each other and jointly form the placenta.

Question 12.
While teaching “reproduction” in the class a student asked the teacher, “Why do human beings not reproduce by binary fission?” As a student of zoology, what will be your answer?
Answer:
A human being is an advanced animal. He reproduces sexually. In man, the newborn is formed by the fusion of sperm (produced by father) and ovum (produced by mother). Binary fission is a type of asexual reproduction found only in primitive animals.

Question 13.
Write the functions of placenta in humans.
Answer:
(a) It helps to supply oxygen and nutrients to the foetus.
(b) It helps in the removal of CO₂ and other waste product formed by the foetus.
(c) Acts as endocrine gland by secreting hormone-like human placental lactogen, human chorionic gonadotropin, estrogen and progesteron which are necessary to maintain pregnancy.

2nd PUC Biology Human Reproduction Three/Five Marks Questions

Question 1.
Describe the accessary ducts of human male reproductive system.
Answer:
The accessory ducts include rete testis, vasaefferentia, epididymis and vas deferens.
The seminiferous tubules end as short, straight tubules into rete testis. From the rete testis, 10-20 fine tubules called vasa efferentia leave the testis and open into the epididymis. The epididymis is a single convoluted tubule that is located along the posterior surface of the testis.

The epididymis leads into vas deferens that ascends into the abdomen and loops over the urinary bladder. It receives the ducts of seminal vesicle to form ejaculatory duct, that runs through the prostate and opens into the urethra, just after its origin from the urinary bladder. The urethra receives the ducts of prostrate and bulbourethral glands and runs through the penis to its external opening called urethral meatus.

Question 2.
Name the cells found
(a) inside the seminiferous tubules
(b) outside the seminiferous tubules in the human testis. Mention the function of each of them.
Answer:
(a) Inside the seminiferous tubules are

• Spermatogonial cells
• Sertoli cells

(b) Outside the seminiferous tubules are Ley dig cells.
Functions:

• Spermatogonial cells form spermatozoa.
• Sertoli cells provide nutrition to the germ cells and help in spermiogenesis.
• Ley dig, cells secrete the male sex hormone, testosterone.

Question 3.
During ovulation only one ovum is produced. But during one ejaculation about 200,000,000 sperms are released. Write the significance of increase in the number of sperms.
Answer:
About 200 million (1 million = 10 lakhs) sperms are discharged by a single ejaculation. Since the sperms have to travel a great distance through the female genital tract there is trouble with chemical hazards and mechanical obstacles. Such a huge number of sperms is necessary to ensure a few to reach the anterior part of the fallopian tube, the site of fertilisation. Of the sperms only one sperm succeeds in fertilising the ovum present there.

Question 4.
Describe the structure of mammary glands of a human female with labelled diagram.
Answer:
A mammary gland consists of glandular tissue and variable quantity of fat. The glandular tissue is divided into 15 – 20 mammary lobes and each lobe contains clusters of cells called alveoli, which opens into mammary tubules. The mammary tubules of each be join to form a mammary duct. Several mammary ducts join to form a wider mammary ampulla, which is connected to lactiferous duct through which milk comes out.

Question 5.
(a) Explain the role of ovarian hormones in inducing changes in the uterus during menstrual cycle.
(b) What triggers release of oxytocin at the time of parturition?
Answer:
(a) Estrogen influences the uterus in the follicular phase. The endometrin is regenerated through protection. Progesterone influences the uterus in the luteal phase, the endometrin becomes further thickened and vascular for implantation
(b) Foetal ejection triggers the release of oxytocin.

Question 6.
Describe the events that take place during in fertilization in human being.
Answer:
Fertilization refers to the fusion of a sperm and ovum in humans that occurs in the ampullary isthmic junction of the fallopian tube. When a sperm comes in contact with the zona pellucida of the ovum, it induces changes in the membrane that. blocks the entry of other sperms. The secretions of acrosome help the sperm to digest the zona pellucida and plasma membrane of the ovum and enter into its cytoplasm.

The entry of sperm induces the completion of secondary meiotic division of the secondary oocyte resulting in the formation of a second polar body and a large ootid. The haploid nucleus of the ootid and that of the sperm fuse to form a diploid zygote.

Question 7.
Describe the major steps in the development of a fertilized egg upto complete differentiation into blastocyst ready for implantation.
Answer:

• The mitotic division called cleavage divisions start in the zygote as it moves through the isthmus of fallopian tube towards the uterus.
• The divisions result is 2,4,8,16 daughter cells, called blastomeres; the embryo with 8-16 blastomeres is a solid spherical structure and is called a morula.
• The morula continues to divide and the blastomeres rearrange themselves as it moves further into the uterus.
• As a result a hollow spherical structure, called blastocyst is formed.
• The blastocyst has an outer layer of cells, called trophoblast and an inner group of cells, called inner cell mass attached at one end of the trophoblast.
• The trophoblast layer becomes attached to the endometrium and the inner cell mass gets ready to form the embryo proper.

Question 8.
Draw a labelled diagram showing a human foetus developing within the uterus.
Answer:

Question 9.
A connection between foetal membrane and uterine wall is known as placenta.
a. Mention the functions of placenta.
b. What is the fate of placenta after parturition?
c. Sometimes the expulsion of placenta is followed by bleeding. Give reason.
Answer:
a. Functions of placenta

• It acts as a barrier between the foetus and the mother.
• It acts as an ultrafilter.
• Soluble inorganic and organic materials, nutrients, hormones, antibodies against diphtheria, small pox, scarlet fever, measles etc. can pass through the placenta from mother to foetus.
• It helps in the exchange of gases between the mother and the foetus.
• It helps in the elimination of nitrogenous discharges and other wastes of the foetus.

It acts as an endocrine gland and produces hormones such as HCG, chorionic thyrotropin, chorionic corticotropin, chorionic somatomammotropin, estrogens and progesterone. It also secretes progesterone until the end of pregnancy. At the time of parturition, the placenta secretes relaxin, which helps in the relaxation of pubic ligaments to enable birth of the child.

b. Shortly after the baby is born, the placenta and the remains of the umbilical cord, known as the afterbirth is expelled out.

c. Because the vascular tissues are damaged in the process of parturition.

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