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Questions
Give the importance of variation in survival of species.
Why is variation important for a species?
Solution
Importance of variation in survival of species:
- Variations result in variety and diversity.
- Due to adaptive variations, organisms are able to survive in changed environmental conditions.
- It prevents complete extinction of any species.
- Evolution continues through these variations and adaptations.
RELATED QUESTIONS
Which mode of reproduction gives rise to variation?
Complete the following table to get the differences between asexual and sexual reproduction:
| Characteristics | Asexual Reproduction | Sexual Reproduction |
| Number of parents involved | ........................... | .............................. |
| Type of cells involved | Somatic cells | Germ cells |
| Type of cell division | ............................ | Meiosis and mitosis |
Name two main processes of sexual reproduction
No two individuals are absolutely alike in a population. Why?
Write one difference between asexual and sexual mode of reproduction.
How do organisms, whether reproduced asexually or sexually maintain a constant chromosome number through several generations? Explain with the help of suitable example.
Define Reproductive phase
Define Senescent phase.
Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?
Internal fertilisation occurs ______.
A new human individual develops from a cell called gamete.
An embryo is made up of a single cell.
In which female reproductive organ does the embryo get embedded?
Differentiate between internal fertilization and external fertilization.
List any four steps involved in sexual reproduction .
Fill in the following blank with suitable word :
The cells involved in sexual reproduction are called .............
Fill in the following blank with suitable word :
A multicellular animal starts its life from a ........... through sexual reproduction.
In which sort of reproduction are gametes involved?
What is formed when two gametes fuse?
What would be the ratio of chromosome number between an egg and its zygote?
The advantage that internal fertilisation has over external fertilisation is that in internal fertilisation :
(a) new off-springs are exactly like the parent
(b) production of large numbers of gametes is unnecessary
(c) copulation and fusion of gametes is passive
(d) fewer individuals are produced
The correct sequence of organs in the male reproductive system for the transport of sperms is:
(a) testis → vas deferens → urethra
(b) testis → ureter → urethra
(c) testis → urethra → ureter
(d) testis → vas deferens → ureter
Put a tick mark (✓) against the correct alternative in the following statement:
Which one of the following represents the correct sequence in the life history of a butterfly ?
- Egg → Larva → Adult → Pupa
- Egg → Pupa → Adult → Larva
- Egg → Larva → Pupa → Adult
- Egg → Pupa → Larva → Adult
Define the term Puberty.
Multiple choice question. Tick (✓) the correct choice:
Which of the following glands is responsible for bringing about changes during adolescence in boys and girls?
- pituitary
- adrenal
- thyroid
- testis
Define the term Adolescence.
Mention the common method of reproduction in Flatworm.
Describe the various stages in the life cycle of a butterfly.
Answer the following question.
It is commonly observed that parents feel embarrassed to discuss freely with their adolescent children about sexuality and reproduction. The result of this parental inhibition is that the children go astray sometimes.
Explain the reasons that you feel are behind such embarrassment amongst some parents to freely discuss such issues with their growing children.
Answer in one sentence.
Outline the path of sperm upto the urethra.
Give an account of external genitalia in human females.
Identify the labels from the given diagram.
Choose the correct statement from the following:
Choose the correct statement from the following
What is parthenogenesis? Give two examples from animals
______ is the first stage of sexual reproduction.
______ lay thousands and sometimes millions of small, soft eggs in water.
The eggshell protects the ______ from the outer environment.
In ______ animals, the development of the embryo takes place inside the body.
Sexual reproduction is characterized by ______
'Fertilisation is not an obligatory event for fruit production in certains plants'. Explain the statement.
Suggest a possible explanation why the seeds in a pea pod are arranged in a row, whereas those in tomato are scattered in the juicy pulp.
Justify the statement ‘Vegetative reproduction is also a type of asexual reproduction’.
Enumerate the differences between asexual and sexual reproduction. Describe the types of asexual reproduction exhibited by unicellular organisms.
Explain how stability of the DNA of the species is ensured in sexually reproducing organisms.
