NCERT Textbook Solved Question For Board Exam | Reproduction in Organisms

👉 NEET Biology Examination 

👉 NEET Biology Tips

👉 NEET Biology Study Material

👉 UGC Net Study Material

Q1. Why is reproduction essential for organisms?

• Reproduction is essential for continuity of generation over long period, usually thousands of years.

Q2. Which is a better mode of reproduction: sexual or asexual? Why?

• Sexual reproduction is better mode of reproduction.
• Because these are variations which contribute to evolution of the species and offsprings are better adapted in the environment.

Q3. Why is the offspring formed by asexual reproduction referred to as clone?

• The offsprings formed by asexual reproduction are genetically identical to each other, hence are called clone.

Q4. Offsprings formed due to sexual reproduction have better chances of survival. Why?

• Sexual reproduction combines the characters of two parents and introduces variations which make the offsprings better in environmental adaptation.

Q5. How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction?

• The progeny formed from asexual reproduction is the product of single parent and does not have genetic variations.

Q6. Distinguish between asexxual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction?

• Asexual Reproduction
• 1. It is always uniparental.
• 2. There is no formation and fusion of gametes.
• 3. Only mitotic cell division takes place.
• 4. Offsprings are genetically identical to the parents.

• Sexual Reproduction
• 1. It is usually biparental.
• 2. Formation and fusion of gametes take place.
• 3. It involves both meiosis and mitosis.
• 4. Offsprings genetically differ from the parents.

• Vegetative reproduction involves single parent and its offsprings are genetically identical hence it is considered as a type of asexual reproduction.

Q7. What is vegetative propagation? Give two suitable examples.

• The process of multiplication, in which parts or fragments of the plant act as reproductive unit or propagule to form new individuals is called vegetative propagation. Examples: (i) Buds (eyes) of Potato (ii) Rhizome of Ginger

Q8. Define (a) Juvenile phase, (b) Reproductive phase, (c) Senescent phase.

• (a) Juvenile phase: Before reacting sexual maturity all organisms have to undergo a proper phase of physical growth. This phase is called juvenile phase. In human the juvenile phase lasts up to 12 to 13 years of age.
• (b) Reproductive phase: Once reproductive system is mature enough to produce male and female gametes the organism is ready to mate and reproduce. This phase is called reproductive phase. Some major hormonal changes mark this phase. In human the reproductive phase starts at about 12 to 13 years and lasts up to 55 to 60.
• (c) Senescent phase: After the reproductive phase the hormonal changes gradually slow down the production of male and female gametes. This phase is called the senescent phase.

Q9. Explain why meiosis and gametogenesis are always interlinked?

• The gametes produced by gametogenesis are always haploid and it is necessary that meiosis has to occur for the formation of haploid gametes because it is reductional division and ensures half number of chromosomes in the developing gametes.

Q10. Define external fertilization. Mention its disadvantages.

• In most aquatic organisms such as algae, fishes and amphibians, syngamy occurs outside the body of organism in the external medium (water).
• This type of gametic fusion is called external fertilization. Ans.
• Disadvantage: Many of the offsprings are not protected from the predators and their survival is threatened upto adulthood.

Q11. Differentiate between gametogenesis and embryogenesis.

• Gametogenesis
• 1.By this process, male and female gametes are formed.
• 2. It involves meiosis.
• Embryogenesis
• 1. It is the process of development of embryo from zygote.
• 2. It involves mitosis.

Q12. Describe the post fertilization change in a flower.

• After fertilization the following changes occur in a flower Zygote is formed inside the ovule and develops into the embryo.
• The ovules develop into the seed. The ovary develops into the fruit. Ovary wall is transformed into a protective layer, pericarp.

Q13. What is a bisexual flower? Collect five bisexual flowers from your neighbourhood and with the help of your teacher find out their common and scientific names.

• A flower bearing both male and female organs (stamens, carpels) is called bisexual flower. Examples: Pea, Mustard, Petunia, tomato, etc.

Q14. 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?

• Cucumber are good examples of cucurbita. Cucumber plants have separate male and female flower.
• Pistillate flower is distinct by appearance of a baby fruit at the base of the flower, while male or staminate flower does not possess such baby fruit.
• Another example of a unisexual flower is flower of maize. The male flower in maize is higher up the stem, while the female flower remains on the lower part of the stem.

Q15. Why are offsprings of oviparous animals at a greater risk as compared to offspring of viviparous animals?

• Eggs cannot move on their so they are greater risk by different types of predators.

========================================

Mail- indiabiologymanishmevada@gmail.com

Connect with this mail for more knowledge of Biology

This Site helpful for UGC Net Examination 

It is also helpful for MCAT (Medical College Admission Test) united States, Australia, Canada and caribbean islands.

For Join With Me Mail Me 

Manish Mevada

M.Sc, M.Phil, B.Ed

THANK YOU.