MP Board Class 12th Biology Solutions Chapter 1 Reproduction in Organisms

Reproduction in Organisms NCERT Textbook Questions and Answers

Question 1.
Why is reproduction essential (necessary) for organisms?
Answer:
Reproduction enables the continuity of the species, generation after generation.

Question 2.
Which is a better mode of reproduction sexual or asexual? Why?
Answer:
The sexual mode of reproduction is better because it is biparental reproduction and introduces variation among offsprings and their parents due to crossing over and recombination during gamete formation by meiosis.

Question 3.
Why is the offspring formed by asexual reproduction referred to as clones?
Answer:

The term clone is used to describe morphologically and genetically similar individuals. It doesn’t need the production of sex organs.
In asexual reproduction also only one parent is involved in the production of individuals. Newly formed individuals are genetically identical to the parent plant.

Question 4.
Offsprings formed due to sexual reproduction have better chances of survival. Why? Is this statement always true?
Answer:
Offspring formed due to sexual reproduction have better chance of survival because:

The offspring consists of its hybrid characters which may adapt better with the different environments.
Genetic variations are introduced among the offspring, which increases the biological tolerance.
Sexual reproduction occurs in the adverse condition in lower plant kingdom, so sexual spores survive in adverse conditions.
Sexual reproduction may not always show better chances of survival because the offspring may be inferior to the parents.

Question 5.
How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction?
Answer:
The progeny formed from asexual reproduction remain identical to their parents but the offsprings produced by sexual reproduction shows variation due to genetic recombination.

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

S.No.	Asexual reproduction	Sexual reproduction
1.	In this type of reproduction, only one parent is required.	In this type of reproduction two parents of different sexes are required.
2.	Whole-body or a single cell acts as a reproductive unit.	Reproductive units are called gametes which are produced by specific tissues.
3.	Offsprings remain pure, i.e., like their parents.	Offsprings differ from their parents.
4.	It occurs by mitosis cell division.	Gametes are formed by meiosis cell division and zygote develops by mitosis cell division
5.	Variation does not occur.	Variation occurs.

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

It is uniparental reproduction.
There is no involvement of gametes or sex cells.
Cell division and no reductional division take place.
Vegetative propagules are somatic cells.

Question 7.
What is vegetative propagation? Give two suitable examples.
Answer:
It is the process of multiplication where new plants develop from any portion of vegetative organs of plants without involving the seeds. It occurs in lower as well as higher plants. Example: In sweet potato, roots modified into tubes. In ginger and turmeric stem into the rhizome.

Question 8.
Define:
(a) Juvenile phase
(b) Reproductive phase
(c) Senescent phase.
Answer:
(a) Juvenile phase: It is the pre-reproductive in which all organisms require a certain growth and maturity in life before reproducing sexually.
(b) Reproductive phase: Reproductive phase is the phase in the life cycle, where an organism possesses all the capacity and potential to reproduce sexually. It is the end of the juvenile phase or vegetative phase.
(c) Senescent phase: It is the post-reproductive phase in the life cycle where an organism slowly losses the rate of metabolism, reproductive potential and shows deterioration of the physiological activity of the body.

Question 9.
Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?
Answer:
The mode of reproduction helps to introduce now variation in progenies through the combination of the DNA from 2 different individuals. These variations allow the individual to cope up with various environmental conditions and thus make the organisms better suited for the environment.

Question 10.
Explain, why meiosis and gametogenesis are always interlinked.
Answer:
Gametogenesis (formation of male and female gametes) is associated with a reduction in chromosome number thus, the gamete formed contains half chromosome set of the parental cell. So, gametogenesis is interlinked with meiosis because in meiosis reduction of chromosome number from the diploid set (2n) to haploid set (n) takes place.

Question 11.
Identify each part in a flowering plant and write whether it is haploid (n) or diploid (2n).
Answer:
MP Board Class 12th Biology Solutions Chapter 1 Reproduction in Organisms 1

Question 12.
Define external fertilization mention its disadvantages.
Answer:
The fusion of compatible gametes (Male and female) outside the body of an organism is called external fertilization, e.g., in Frog.
Disadvantages of external fertilization:

It requires a medium for fusion of gametes.
The young ones are often exposed to predators.
After fertilization, offsprings are produced large in number but no parental care is provided

Question 13.
Differentiate between a Zoospore and Zygote.
Answer:
Differences between Monera and Protista:

S.No.	Zoospore	Zygote
1.	These are endogenously, asexually	A zygote is a diploid cell formed by fusion
3.	Zoospores take part in dispersal.	The zygote does not have a significant role in dispersal.
3.	Zoospores take part in dispersal.	The zygote does not have a significant role in dispersal.

Question 14.
Differentiate between Gametogenesis and Embryogenesis.
Answer:
Differences between Gametogenesis and Embryogenesis:

S.No.	Gametogenesis	Embryogenesis
1.	It is the formation of gametes from meiocytes.	It is the formation of an embryo from a zygote cell.
2	This is a pre-fertilization event.	This is a post-fertilization event.
3.	It occurs inside reproductive organs.	It occurs outside or inside the female body.
4.	It produces haploid gamete.	It gives rise to diploid embryos.
5.	The cell division during gametogenesis is meiotic in diploid organisms.	The cell division during embryogenesis is mitotic in diploid organisms.

Question 15.
Describe the post-fertilization changes in a flower.
Answer:
After fertilization, the ovule converts into the seed and the whole ovary develops into a complete fruit. The petals and sepals dried and fall off. The fate of other parts is

The ovary wall forms the pericarp of the fruit. It may become fleshy, juicy or dry.
The integument of the ovule is converted into seed coat. The outer integument forms the tesla and the inner into tegmen.
Egg of the ovule divides meiotically and forms the multicellular diploid embryo.
Polar nuclei as a result of triple fusion from the endosperm. It accumulates food and functions as a nutritive tissue for the developing embryo.

Question 16.
What is a bisexual flower? Collect five bisexual flowers from your neighborhood and with the help of your teacher find our their common and scientific names.
Answer:

S.No.	Common Name	Scientific Name
1.	China rose	Hibiscus rosa sinensis
2	Chandni	Ervatamia divaricata
3.	Makoy	Solatium nigrum
4.	Sunflower	Helianthus annuus
5.	Mustard	Brassica compestris.

Question 17.
Examine a few flowers of any cucurbit plant and try to identify the staminate and pistillate flowers. Do you know any other plant that bears unisexual flowers?
Answer:
In oviparous animals, the fertilized egg covered over by a calcareous shell. After a period of enucleation, the egg hatches out into young one i.e. outside the body of the parent. But in viviparous animals, the zygote develops into a young one inside the body of female organism. After attaining the proper development young ones are delivered out of the body of the female organism. Because of getting proper embryonic care and protection, the chances of survival of young one is greater in viviparous animals.

Question 18.
Why are offspring of oviparous animals at a greater risk as compared to offspring of viviparous animals?
Answer:
In viviparous animals, the young one develops inside the body of the female organism. As a result of this, the young one gets better production and nourishment for proper development. In case of oviparous animals, they lay eggs and the young ones develop inside the calcareous shell, outside the body of the female. So, the young ones are not effectively protected and nourished and are vulnerable, to predators so, they are at a greater risk as compared to the offsprings of the viviparous animals.

Reproduction in Organisms Other Important Questions and Answers

Reproduction in Organisms Objective Type Questions

1. Choose the Correct Answers:

Question 1.
Callose wall is found: (CBSE PMT 2007)
(a) In male gamete
(b) In ovum
(c) In pollen grain
Answer:
(d) In megaspore mother cell.

Question 2.
Name the plant in which new plant arise from the notches of leaves through vegetative propagation: (AFMC2012)
(a) Asparagus
(b) Chrysanthemum
(c) Agave
(d) Bryophyllum.
Answer:
(d) Bryophyllum.

Question 3.
Which type of vegetative propagation is occurs in banana: (AMU 2012)
(a) From tuber
(b) From rhizome
(c) From bulb
(d) From stolen.
Answer:
(b) From rhizome

Question 4.
Which of the following is viviparous:
(a) Tortoise
(b) Bony fish
(c) Hummingbird
(d) Whale
Answer:
(d) Whale

Question 5.
Which of the following is characteristics of the ‘clone’:
(a) Similar to ancestors in genetic character
(b) A group of plants developed in vegetative propagation
(c) Plants developed from same parents
(d) All of the above.
Answer:
(d) All of the above.

Question 6.
Organism which give birth to young ones:
(a) Viviparous
(b) Amphibians
(c) Oviparous
(d) Coelomate.
Answer:
(a) Viviparous

Question 7.
Set of chromosome found in zygote:
(a) X
(b) 2X
(c) 3X
(d) 4X.
Answer:
(b) 2X

Question 8.
The plant which can be obtained same as parent plant:
(a) Through seeds
(b) Through fruits
(c) By cutting the stem
(d) By hybridization.
Answer:
(c) By cutting the stem

Question 9.
Vegetative propagation in potato is:
(a) By rhizome
(b) By bulb
(c) By stem
(d) By tuber.
Answer:
(d) By tuber.

Question 10.
Which of the following is oviparous animal:
(a) Bat
(b) Whale
(c) Penguin
(d) Amoeba.
Answer:
(c) Penguin

2. Fill in the Blanks:

Reproductive organs in plants are developed in ……………….. phase.
……………….. nucleus are present in pollen tube of angiosperms.
The ……………….. are not form in Rose and Banana, therefore, reproduction occurs through ………………..
Reproductive organs of animals are differentiate in ……………….. stage.
Eichomia propagate through ………………. in water.
Rate of multiplication is greater ……………….. reproduction than ……………….. reproduction.

Answer:

Adolescence
Three
Seeds, Vegetative propagation
Embryo
Offset
Sexual, Asexual.

3. Match the Following
MP Board Class 12th Biology Solutions Chapter 1 Reproduction in Organisms 2
Answer:

Answer in One Word/Sentence:

What we called uniparental structure formed from asexual reproduction which is genetically and morphologically similar.
Write the name of an algae reproduce by means of zoospores.
Animal reproduce asexually.
What we called spores having flagella.
In Bryophyllum what kind of bud reproduce vegetatively ?

Answer:

Clone
Chlamydomonas
Spongilla
Zoo-spores
Adventitious bud.

Reproduction in Organisms Very Short Answer Type Questions

Question 1.
What is meant by life span ?
Answer:
The period from birth to the natural death of an organism is called life span.

Question 2.
Give definition of fertilization.
Answer:
Fertilization is a process in which male and female gamete fused to form the zygote.

Question 3.
What is clone ?
Answer:
Morphologically and genetically similar individuals who are produced by single parent is called clone.

Question 4.
Give the name of an organism in which asexual reproduction occurs through conidia.
Answer:
Penicillum.

Question 5.
In which plant vegetative propagation occurs through rhizome ?
Answer:
In Ginger, Termeric.

Question 6.
Give the name of an organism in which transverse binary fission occurs.
Answer:Paramoecium.

Question 7.
What is aging ?
Answer:
When humans are not capable for reproduction is known as aging.

Question 8.
Give two examples of Hermaphrodite plants.
Answer:
Cucurbita and Coconut are hermaphrodite plant.