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प्रश्न
Give the importance of variation in survival of species.
Why is variation important for a species?
उत्तर
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.
संबंधित प्रश्न
List six specific characteristics of sexual reproduction.
What is the effect of DNA copying, which is not perfectly accurate, on the reproduction process? How does the amount of DNA remain constant though each new generation is a combination of DNA copies of two individuals?
How do organisms, whether reproduced asexually or sexually maintain a constant chromosome number through several generations? Explain with the help of suitable example.
What is amphimixis?
Each sperm is a single cell.
State the basic requirement for sexual reproduction?
Explain how, in sexually reproducing organisms, the number of chromosomes in the progeny is maintained.
Define sexual reproduction.
What is this act of fusion called?
What would be the ratio of chromosome number between an egg and its zygote?
The figure given alongside shows the human male reproductive organs. Which structures make sperms and seminal fluid?
(a) V makes sperms and X makes seminal fluid
(b) W makes sperms and Y makes seminal fluid
(c) X makes sperms and W makes seminal fluid
(d) Y makes sperms and V makes seminal fluid
Characters that are transmitted from parents to offspring during sexual reproduction show :
(a) only similarities with parents
(b) only variations with parents
(c) both similarities and variations with parents
(d) neither similarities nor variations with parents
Mention the common method of reproduction in Amoeba.
Describe the various stages in the life cycle of a butterfly.
“The chromosomes number of the sexually reproducing parents and their offspring is the same.” Justify this statement.
In the sexual mode of reproduction, greater diversities are generated.
What are seasonal breeders? Give an example.
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.
Answer in one sentence.
Name the endocrine glands involved in maintaining the sex characteristics of males.
Explain the histological structure of testis.
Long answer question.
Describe female reproductive system of human.
What is atresia with respect to ovary in human females?
Identify the labels from the given diagram.
What are the different stages of sexual reproduction?
Choose the correct statement from the following:
Give reason for the following:
Some organisms like honey bees are called parthenogenetic animals
How is juvenile phase different from reproductive phase?
In an ovule, meiosis occurs in ______
Due to presence of which of the following chemical component, pollen grains can remain well preserved in fossil?
Identify the INCORRECT statement.
In sexual reproduction, offsprings resemble the parents ______.
______ is the first stage of sexual reproduction.
Sexual reproduction is characterized by ______
Rose plants produce large, attractive bisexual flowers but they seldom produce fruits. On the other hand a tomato plant produces plenty of fruits though they have small flowers. Analyse the reasons for failure of fruit formation in rose.
Both these plants - rose and tomato - both selected by human beings for different characteristics, the rose for its flower and tomato for its fruit. Roses, being vegetatively propagated do not need to produce seeds.
Explain how stability of the DNA of the species is ensured in sexually reproducing organisms.
