1st PUC Biology Question Bank Chapter 2 Biological Classification

   

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Karnataka 1st PUC Biology Question Bank Chapter 2 Biological Classification

1st PUC Biology Biological Classification NCERT Text Book Questions and Answers

Question 1.
Discuss how classification systems have undergone several changes over a period of time?
Answer:

  1. Different systems of classification proposed from time to time have undergone several changes from artificial system to phylogenetic system earlier the system of classification was based on one or a few superficial resemblances.
  2. For example, animals were classified as aquatic (water dwellers), terrestrial (land dwellers) and aerial (air dwellers).
  3. Similarly, plants were classified as herbs, shurbs and trees on the basis of their habit. This system is artificial.
  4. The artificial system was then followed by natural system which were based on a number of structural and morphological taxonomic characters.
  5. Now, the organisms are classified ! on the basis of their evolutionary interrelationship. Such classification are phylogenetic.

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Question 2.
State two economically Important uses of:
(a) heterotrophic bacteria
(b) archaebacteria
Answer:
(a) Heterotrophic bacteria:

  • Nitrogen fixation in roots of leguminous plants
  • Being decomposers, used in the production of antibiotics

(b) Archaebacteria:

  • Production of biogas from cow-dung.
  • Lives in the guts of ruminant animals & help them in the digestion of starch.

Question 3.
What Is the nature of cell-walls in diatoms?
Answer:
The cell wall of diatoms is covered by a transparent siliceous shell (silica deposited in the cell wall which is composed of cellulose) known as a frustule.

Question 4.
Find out what do the terms ‘algal bloom’ and ‘red tides signify.
Answer:
Red-tides Some Dianoflagellates have red pigments in their cells. They multiply rapidly. These marine organisms make a red sheet overseas, Thus look red-tides. Algal bloom Colonies of cyanobacteria like Nostoc Anabaena form blooms in polluted water bodies are called algal bloom.

Question 5.
How are viroids different from viruses?
Answer:
Viroids are free RNAs without protein Coat, whereas, viruses have RNAs encapsulated in a protein coat.

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Question 6.
Describe briefly the four major groups of Protozoa.
Answer:
(a) Amoeboid protozoa:
These organisms live in freshwater, seawater, or moist soil. They move and capture their prey by putting out pseudopodia (false feet) as in Amoeba. Marine forms have silica shells on their surface. Some of them such as Entamoeba are parasites.

(b) Flagellated protozoa:
The members of this group are either free-living or parasitic. They have flagella. The parasitic forms cause diseases such as sleeping sickness. Example: Trypanosoma.

(c) Ciliated protozoa:
These are aquatic, actively proving organisms because of the presence of thousands of cilia. They have a cavity (gullet) that opens to the outside of the cell surface. The co-ordinated movement of rows of cilia causes the water laden with food to be steered into the gullet. Example: Paramecium
1st PUC Biology Question Bank Chapter 2 Biological Classification 1

(d) Sporozoans: This includes diverse organisms that have an infectious spore-like stage in their life cycle. The most notorious is Plasmodium which causes malaria which has a staggering effect on the human population.

Question 7.
Plants are autotrophic. Can you think of some plants that are partially heterotrophic?
Answer:
Insectivorous plants are partly heterotrophic.

Question 8.
What do the terms phycobiont and mycobiont signify?
Answer:
Lichens are the symbiotic association between algae and fungi. The fungal component is called mycobiont and the algae component is known as phycobilins.

Question 9.
What are the characteristic features of Euglenoids?
Answer:
Characteristic of Euglenoids:

1st PUC Biology Question Bank Chapter 2 Biological Classification 2

  • freshwater organisms found in stagnant water.
  • Instead of a cell wall, they have a protein-rich layer called a pellicle which makes their body flexible.
  • They have two flagella, a short and a long one.
  • They are photosynthetic in the presence of sunlight but behave like heterotrophs by predating on other small organisms in absence of sunlight.
  • pigments are identical to those present in higher plants. Example: Euglena

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Question 10.
Give a brief account of viruses with respect to their structure and the nature of genetic material. Also, name four common viral diseases.
Answer:
Viruses have protein capsules and genetic material inside. Viruses are non-cellular organisms that are characterized by having an inert crystalline structure outside the living cell. Once they infect a cell they take over the machinery of the host cell to replicate themselves killing the host.

1st PUC Biology Question Bank Chapter 2 Biological Classification 3
Generally, a protein that infects plants has single standard RNA and Viruses that infect animals have either single or double-stranded DNA. Bacteriophages usually have double-stranded DNA. Whereas TMV contains single-stranded RNA. Four common Viral diseases

  • AIDS
  • Mumps
  • Small Pox
  • Harpies

Question 11.
Give a comparative account of the classes of Kingdom Fungi under the following:
(i) mode of nutrition
(ii) mode of reproduction
1st PUC Biology Question Bank Chapter 2 Biological Classification 4

Question 12.
Organize a discussion in your class on the topic-Are viruses living or nonliving?
Answer:
Viruses are linked between living and non-living. They possess some living characters and some non-living characters. Crystallization is a non-living character but it can reproduce inside a living body. Actually, they are metabolic ly inert when outside the host-cell. They reproduce using the metabolic machinery of the host cell and infect chemically.

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