CBSE Class 10 Science Chapter 9 Heredity And Evolution Very Short Answer Questions

Question 1. Name one reptile in each case where a higher incubation temperature leads to the development of

1. Male progeny
2. Female progeny.

Answer:

1. Lizard
2. Turtle

Question 2. What are the carriers of factors or genes?
Answer: Chromosomes.

Question 3. Which type of sex chromosomes are carried by male gametes in human males? What is their percentage?
Answer: X and Y chromosomes. 50% of sperms carry X chromosomes and 50% carry Y chromosomes.

Question 4. An organism which is a worm, has very simple ‘eyes’, which are eye spots that detect light. Name that organism.
Answer: Planaria.

Question 5. Why is the progeny always tall when a tall pea plant is crossed with a short pea plant?
Answer: The trait that represents the tallness in a pea plant is dominant over the other trait shortness.

Question 6. What is heredity?
Answer: Transmission of characters from parents to their offspring.

Question 7. Mendel observed the contrasting traits of the position of flowers. Mention those traits.
Answer:

1. Terminal → Recessive and
2. Axial → Dominant

Question 8. How can the chromosomes be identified?
Answer: In human beings, the individual chromosomes are identified by their length, position of centromere, and banding pattern on staining.

Question 9. Where does the process of gene flow take place?
Answer: Gene flow or gene migration takes place between populations that are partly but not completely separated.

Question 10. How many pairs of chromosomes are present in human beings?
Answer: 23 pairs.

Question 11. What is the phenotype ratio of a dihybrid cross in F₂ generation?
Answer: 9:3:3:1

Question 12. Give the respective scientific terms used for studying:

1. The mechanism by which variations are created and inherited.
2. The development of new types of organisms from the existing ones.

Answer:

1. Heredity
2. Species.

Question 13. What type of reproduction gives rise to more number of successful variations?
Answer: Sexual reproduction.

Question 14. What will be the sex of a child who inherits X chromosomes from his/her father?
Answer: Female.

Question 15. No two individuals are alike in a population. Why?
Answer: All individuals have different kinds of DNA. So all individuals are not alike to each other.

Question 16. Define speciation
Answer: Speciation means the origin of a new species from the existing one.

Question 17. Define evolution.
Answer: A gradual genetic change in a group of living beings to produce new forms.

Question 18. Give an example where sex determination is regulated by environmental factors.
Answer: In snails, sex is determined by environmental factors (temperature).

Question 19. Name the term used for the traits that are exhibited externally.
Answer: Phenotype.

Question 20. Write the sex of the baby that inherits Y chromosomes from the father.
Answer: Male.

Question 21. Are the wings of a butterfly and the wings of a bat analogous organs or homologous organs? Justify your answer.
Answer: Analogous. They are analogous as they have the same function but different basic structures.

Question 22. What are fossils?
Answer: Preserved traces of living organisms.

Question 23. What is genetic drift?
Answer: The change in the frequency of certain genes in a population over generations.

Question 24. Name any three different traits the pea plant possesses.
Answer: Round and wrinkled seeds Tall and short plant white and violet flowers i.e., seed shape, plant height, flower color.

Question 25. What are the basic events in evolution?
Answer: The changes in DNA during reproduction are the basic events in evolution.

Question 26. What are analogous organs?
Answer: The organs that have similar functions but different structures are called analogous organs

Question 27. Name the plant on which Mendel performed his experiments.
Answer: Garden pea.

Question 28. Give an example of a homologous organ from the plant kingdom.
Answer: Thorns and tendrils.

Question 29. Name the genetic material that is responsible for the inheritance of traits.
Answer: Gene.

Question 30. What is a gene?
Answer: It is the unit of inheritance. Gene is the part of a chromosome that controls the appearance of a set of hereditary characteristics.

Question 31. Species A shares ten characteristics with species B, and species C shares fifteen characteristics with D, which of the two pairs shares a closer relation?
Answer: C and D