Heredity and Evolution


What are the chromosomes XY and XX known as ?


Sex Chromosomes.


Heredity and Evolution

Q 1.

Name the scientist who gave the theory of evolution.

Q 2.

Mention three important features of fossils which help in the study of evolution.

Q 3.

How are fossils formed? Describe, in brief, two methods of determining the age of fossils. [All India]

Q 4.

a) Name the scientist who gave the theory of origin of life on earth. What is this theory ?
(b) How are those species which are now ‘extinct’ studied ?

Q 5.

If the trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier ?

Q 6.

(a) If a normal human cell has 46 chromosomes, how many chromosomes will be there in a human (;) sperm cell, and (ii) zygote ?
(b) What sizes of plants are produced if both parents have genes Tt ?

Q 7.

Where did life originate on the earth ?

Q 8.

Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually ? Why or why not ?

Q 9.

Define variation in relation to a species. Why is variation beneficial to the species? [Delhi]

Q 10.

Explain with examples how the following are evidences in favour of evolution in organisms.  (i) Homologous organs (ii) Analogous organs (iii) Fossils [Delhi]

Q 11.

What is meant by the term speciation? List four factors which could lead to speciation. [Delhi]

Q 12.

What are the chromosomes XY and XX known as ?

Q 13.

What are the four blood groups in humans ?

Q 14.

Name two organisms which are now extinct and studied from their fossils.

Q 15.

Match the terms given in column I with those given in column II :

Q 16.

A woman has only daughters. Analyse the situation genetically and provide a suitable explanation.

Q 17.

Describe the different types of chromosomes.

Q 18.

How do homologous organs provide evidence in support of evolution?

Q 19.

What is a sex chromosome?

Q 20.

The human beings who look so different from each other in terms of colour, size and looks are said to belong to the same species. Why? Justify your answer. [All India(C)]

Q 21.

Give an example of body characteristics used to determine how close two species are in terms of evolution and explain it. [All India]

Q 22.

A new born child has an XY pair of chromosmes. Will it be a baby boy or a baby girl ?

Q 23.

The gene for red hair is recessive to the gene for black hair. What will be the hair colour of a person if he inherits a gene for red hair from his mother and a gene for black hair from his father ?

Q 24.

(a) What will you get in the F1 and F2 generations in the following cross ?
Pure tall pea plant x Pure dwarf pea plant
(b) Is it an example of monohybrid cross or dihybrid cross ?

Q 25.

(a) What is the genotype of dwarf plants which always produced dwarf offspring ?
(b) What is the genotype of tall plants which always produced tall offspring ?
(c) What is the genotype of

  1.  dwarf plants, and
  2.  tall plants, whose parental cross always produces tall offspring ?

Q 26.

Name the various tools of tracing evolutionary relationships which have been used for studying human evolution.

Q 27.

Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement ? Why or why not ?

Q 28.

What is heredity?

Q 29.

Define a gene.

Q 30.

With the help of suitable examples explain natural selection. [Foreign]

Q 31.

How is the equal genetic contribution of male and female parents ensured in the progeny? [Delhi]

Q 32.

State whether the following statement is true or false :
The sex of an infant is not a case of inheritance of characteristics.

Q 33.

Name the first scientist who studied the inheritance of traits from one generation to the next.

Q 34.

Give the contrasting traits of the following characters in pea plant and mention which is dominant and which is recessive :
(a) Yellow seed (b) Round seed

Q 35.

(a)What is meant by ‘heredity’ ? What are the units of heredity.
(b) State Mendel’s first law of inheritance.

Q 36.

(a) Why did Mendel choose pea plants for conducting his experiments on inheritance ?
(b) State Mendel’s second law of inheritance.

Q 37.

Fill in the following blanks with suitable words :Fill in the following blanks with suitable words :
(a) The human forelimb and bat’s forelimb are an example of……………………organs whereas an insect’s wing and a bat’s wing are an example of…………………organs.
(b) The evolution of eye is an example of evolution by…………………
(c) The scientific name of all human beings is……………………..
(d) Broccoli has evolved from…………… the process of artificial selection.
(e) The theory of natural selection for evolution was proposed by………………………

Q 38.

(a) Define ‘speciation’. Explain how speciation occurs.
(b) Will geographical isolation be a major factor in the speciation of a self-pollinating plant species ? Give reason for your answer.

Q 39.

Give reasons why acquired characters are not inherited.

Q 40.

Evolution has exhibited a greater stability of molecular structure when compared with morphological structures. Comment on the statement and justify your opinion.

Q 41.

How does the creation of variations in a species promote survival ?

Q 42.

What are fossils ? What do they tell us about the process of evolution ?

Q 43.

What are the components of the chromosome?

Q 44.

What do you understand by the double helical structure of DNA? Who proposed this structure?

Q 45.

Gregor Mendel’s first law of genetics states “Of a pair of contrasted characters, only one can be represented in a gamete by its internal ‘factor’.
(a) Give the modern name for this ‘factor’.
(b) State where these factors are found in gametes.

Q 46.

Does genetic combination of mother play a significant role in determining the sex of a new born baby ?

Q 47.

The forelimbs of a frog, a bird and a man show the same basic design (or basic structure) of bones. What name is given to such organs ?

Q 48.

Out of the wing of a bird, wing of an insect and the wing of a bat :
(a) which two are homologous organs ?
(b) which two are analogous organs ?

Q 49.

What are fossils ? Giving one example, explain how fossils provide evidence for evolution.

Q 50.

Out of bacteria, spider, fish and chimpanzee, which organism has a better body design in evolutionary terms ? Give reason for your answer.