12th Bio Zoology Guide Chapter 1 Reproduction in Organisms Text Book Back Question and Answers

12th Bio Zoology Guide 

Chapter 1 -  Reproduction in Organisms

Text Book Back Questions and Answers

1.In which type of parthenogenesis are only males produced?

(a) Arrhenotoky
(b) Thelytoky
(c) Amphitoky
(d) Both a and b
Answer:
(a) Arrhenotoky

2.Animals giving birth to young ones:

(a) Oviparous
(b) Ovoviviparous
(c) Viviparous
(d) Both a and b
Answer:
(c) Viviparous

3.The mode of reproduction in bacteria is by ……………..

(a) Formation of gametes
(b) Endospore formation
(c) Conjugation
(d) Zoospore formation
Answer:
(c) Viviparous

4.In which mode of reproduction variations are seen?

(a) Asexual
(b) Parthenogenesis
(c) Sexual
(d) Both a and b
Answer:
(c) Sexual

5.Assertion and reasoning questions:

In each of the following questions there are two statements. One is assertion (A) and other is reasoning (R). Mark the correct answer as
A. If both A and R are true and R is correct explanation for A
B. If both A and R are true but R is not the correct explanation for A
C. If A is true but R is false
D. If both A and R are false

I. Assertion: In bee society, all the members are diploid except drones.
Reason: Drones are produced by parthenogenesis.
A B C D
Answer:
(I) A
II. Assertion: Offsprings produced by asexual reproduction are genetically identical to the parent.
Reason: Asexual reproduction involves only mitosis and no meiosis.
A B C D
Answer:
(II) A
III. Assertion: Viviparous animals give better protection to their offsprings.
Reason: They lay their eggs in the safe places of the environment.
A B C D
Answer:
(III) C

6.Name an organism where cell division is itself a mode of reproduction.

Answer:
Amoeba

7.Name the phenomenon where the female gamete directly develops into a new organism with an avian example.

Answer:
Parthenogenesis is the phenomenon where the unfertilized female gamete (egg) develops into a new individual.
e.g. Turkey

8.What is parthenogenesis? Give two examples from animals.

Answer:
Development of an egg into a complete individual without fertilization is known as parthenogenesis. It was first discovered by Charles Bonnet in 1745.
E. g. Honey bees, Aphis.

9.Which type of reproduction is effective – Asexual or sexual and why?

Answer:
Sexual reproduction is highly effective than asexual reproduction since the offsprings produced are genetically different from parents causing variations. Variation leads to evolution.

10.The unicellular organisms which reproduce by binary fission are considered immortal. Justify.

Answer:
In unicellular organisms during binary fission, the entire cell (organism) divides completely to form two daughter cells which later on develop into adult and the process goes on repeatedly during each division leading to immortality of cell (organism). Hence unicellular organisms like amoeba are ‘biologically immortal’.

11.Why is the offspring formed by asexual reproduction referred as a clone?

Answer:
Offsprings developed by asexual reproduction are referred to as clones since they are genetically & morphologically similar to this parent.

12.Why are the offsprings of oviparous animal at a greater risk as compared to offsprings of viviparous organisms?

Answer:
Oviparous animals are egg-layers. The eggs containing embryo are laid out of their body and are highly susceptible to environmental factors (temperature, moisture etc.) and predators. Whereas, in viviparous animals, the embryo develops inside the body of female and comes out as young ones. Hence offsprings of oviparous animals are at risk compared to viviparous animal.

13.Give reasons for the following:

Some organisms like honey bees are called parthenogenetic animals
A male honey bee has 16 chromosomes whereas its female has 32 chromosomes
Answer:
Among honey bees, the queen bee and worker bees develop from fertilized eggs whereas the drones develop from unfertilized eggs. Hence the honey bees are parthenogenetic animals showing incomplete parthenogenesis.
Female honey bees (Queen or worker bees) are diploid having 32 chromosomes since they develop from the fertilized egg. On the other hand, the male honey bees (drones) develop from unfertilized egg possessing only 16 chromosomes (i.e., Haploid)

14.Differentiate between the following:

(a) Binary fission in amoeba and multiple fission in Plasmodium
(b) Budding in yeast and budding in Hydra
(c) Regeneration in lizard and Planaria
Answer:
(a) Binary fission in amoeba and multiple fission in Plasmodium
Binary fission in amoeba
In binary fission of amoeba, the plane of division is hard to observe. The nucleoli disintegrates. The nucleus divides mitotically forming two nucleus. The cell constricts in middle, so the cytoplasm divides forming two daughter cells.
Multiple fission
In Multiple fission of plasmodium, the oocyte or schizont divides into many similar daughter cells simultaneously. Nucleus undergoes repeated mitosis producing many nuclei without the division of cytoplasm. Later the cytoplasm divides & encircles each nucleus forming many daughter cells oocyte undergoes sporogony forming sporozoites. Schizont undergoes schizogony forming merozoites.
(b) Budding in yeast and budding in Hydra
Budding in Yeast
Yeast is xxxx cellular organism in which the bud develops as a small protuberance following the nuclear division and finally detached to new individual
Budding in Hydra
Hydra is a multicellular organism where the bud xxxxxx from the parents body, grows gradually and finally gets detached.
(c) Regeneration in lizard and Planaria
Regeneration of Lizard
If the tail of the lizard is cut and removed, a new tail will regenerate in damaged part. In lizard only the new tail is regenerated.
Regeneration of Planaria
If a planarian worm get cut then each half regenerates the lost part resulting in two worms.
In planaria, the cut removed part developed into an entire worm.

15.How is juvenile phase different from reproductive phase?

Answer:
Juvenile phase
Juvenile phase is the period of growth between the brith of an organism and before its reproductive maturity
Reproduction phase
Reproductive phase is the period of growth after juvenile phase when an individual attain reproductive maturity and reproduces.

16.What is the difference between syngamy and fertilization?

Answer:
Syngamy & fertilization both are more similar terms with a difference that syngamy refers to the process of fusion of two gametes forming zygote while fertilization refers to the process of being fertile.