2nd PUC Biology Question Bank Chapter 1 Reproduction in Organisms

   

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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.

KSEEB Solutions

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.

KSEEB Solutions

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.

KSEEB Solutions

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).

KSEEB Solutions

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.
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