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 enables the continuity of the species, generation after generation.

Question 2.
Which is better mode of reproduction: sexual or asexual? Why ?
Answer:
Sexual. It brings genetic variation and inherited during reproduction. It helps to create new species.

Question 3.
Why is the offspring formed by asexual reproduction referred to as clone ?
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 for the production of individual. Newly formed individuals are genetically identical to the parent plant.

Question 4.
Off springs formed due to sexual reproduction have better chances of survival. Why ? is this statement always true ?
Answer:
Yes. Because sexual reproduction brings changes in the genetic structure which leads to variation. This helps the organism to adjust or adapt according to the changes in the environment.

Question 5.
How does the progeny formed from asexual reproduction differ from those formed by asexual 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.

KSEEB Solutions

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

Asexual Reproduction Sexual Reproduction
1.  Only single parent is involved for the production of new individuals.
2. All divisions are mitotic.
3. It doesn’t need 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 arises from fusion of two gameteseach contributed by one parent.
2.  It undergoes meioses at one or other 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:
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 rhizome.

Question 8.
Define
(a) Juvenile phase
(b) Reproductive phase
(c) Senescent phase
Answer:
(a) Juvenile phase: The period of growth is called the juvenile phase. It is known as vegetative phase in plants.
(b) Reproductive phase: The phase during which the organisms are able to produce their offsprings.
(c) Senescent phase: The period during which the organisms loss their ability to produce their offspring.

Question 9.
Higher organisms have resorted to sexual reproduction inspite 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 meioses and gametogenesis are always interlinked ?
Answer:
Gametogenesis is the process of the production of gametes. Gamates are haploid in nature produced from diploid gametic cells. Diploid cell undergoes meiotic division followed by mitotic division produces gametes.

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:
The fertilization which involves the union of an egg with the sperm outside the body of the female is called external fertilization. It generally takes place in the medium of water. There is a chance of loss of male gamete during transport in water which leads to failure of external fertilization. Therefore the number of male gametes produced is several thousand times the number of female gametes produced.

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 gamates. Zygote is deploid in nature.

Question 14.
Differentiate between gametogenesis and embryogenesis.
Answer:

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

Question 15.
Describe the post fertilisation 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 multicellular diploid embryo.
  • Polar nuclei as a result of triple fusion from endosperm. It accumulates food and functions as a nutritive tissue for the developing embryo.

Question 16.
What is a bisexual flower ? Collect 5 bisexual flowers from your neighbourhood . and write common and scientific names.
Answer:
The flower in which both reproductive organs i.e. stamen and pistil 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 a great risk as compared to offspring of viviparous animals.
Answer:
In oviparous animals, the fertilized egg covered over by calcareous shell. After a period of enucleation the egg hatches out into young one i.e. out side the body of parent. But in viviparous animals, zygote develops into 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.
Examine a few flower of any cucurbit plant and try to identity the staminate and pistillate flowers. Do you know any other plant bears unisexual flowers.
Ans:
Other unisexual plants are com, papaya, cucumber etc.

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.
Ans :
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 clone ?
Answer:
Morphologically and genetically similar individuals produced by a single parent. In this young ones are 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 adult.

Question 6.
Name the type of reproduction 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 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 oestrus cycle ?
Answer:
It is a heat period during which sexual desire of the female animal is at peak.

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

KSEEB Solutions

Question 13.
Give the events 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 is sperm and ovum.

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

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

Question 19.
Differentiate between staminate and pistillate flower.
Answer:
Unisexual male flower is staminate. 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 occur in meioeytes (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 which results the formation of zygote.

2nd PUC Biology Reproduction in Organisms Two Marks Questions

Question 1.
Differentiate between staminate and pistillate flower. Give the term for this condition of flower.
Answer:

  • The unisexual male flower is called staminate, which bears only stamen.
  • The unisexual female flower is called pistillate, which bears only pistil.
  • Heterothallic or dioecious are the terms used to describe this condition.

Question 2.
Explain parthenogenesis with examples.
Answer:
The process of development of new organism from female gamete without fertilization is called parthenogenesis. 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 takes place as there is no homologous chromosome. Therefore only mitotic division takes place.

Question 4.
In Ashes as well as amphibians where does syngamy occur. What type of fertilization occurs.
Answer:
In lower animals like fishes and amphibians syngamy occurs outside the body i.e., in water media. Therefore the type of fertilization is external fertilization.

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 adult hood.