Biology

Heredity and Evolution

Question:

Bacteria have a simpler body plan when compared with human beings. Does it mean that human beings are more evolved than bacteria? Provide a suitable explanation.

Answer:

Both bacteria and human beings perform all activities of life to live in their environment. Human beings have more complex organisation and differentiation which are absent in bacteria. Since, complexity and differentiation develop only through evolution, humans are more evolved than bacteria.

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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.

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

Q 4.

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

Q 5.

A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?

Q 6.

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 7.

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

Q 8.

What do the following symbols used in the topic on heredity represent ?
(a) TT
(b) tt
(c) XX
(d) XY

Q 9.

(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 10.

In a human, how many chromosmes are present in :
(a) a brain cell ?
(b) a sperm in the testes ?
(c) an egg which has just been produced by the ovary ?
(d) a skin cell ?
(e) a fertilised egg ?

Q 11.

(a) What do you understand by the term ‘variation’ ?
(b) Name two human traits which show variation.

Q 12.

Name two animals having homologous organs and two having analogous organs. Name these organs.

Q 13.

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 14.

What evidence do we have for the origin of life from inanimate matter?

Q 15.

What is heredity?

Q 16.

Explain Darwin's theory of evolution.

Q 17.

What is a sex chromosome?

Q 18.

If we cross pure-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant we will get pea plants of F1 generation. If we now self-cross the pea plant of F2   generation, then we obtain pea plants of F2   generation.
(a) What do the plants of F2 generation look like?
(b) State the ratio of tall plants to dwarf plants in F2 generation.
(c) State the type of plants not found in F2 generation but appeared in F2 generation, mentioning the reason for the same. [All India]

Q 19.

State the meaning of inherited traits and acquired traits. Which of the two is not passed on to the next generation? Explain with the help of an example.

Q 20.

What constitutes the link between one generation and the next ?

Q 21.

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 22.

What are the four blood groups in humans ?

Q 23.

Fill in the following blanks with suitable words :Fill in the following blanks with suitable words :
(a) Genes always work in …………………
(b) In pea plants, the gene for dwarfness is………………… whereas that for tallness is…………………
(c) Most people have………………… earlobes but some have………………… earlobes.
(d) A human gamete contains………………… chromosomes whereas a normal body cell has………………… chromosomes in it.
(e) All races of man have………………… blood groups.
(f) The………………… chromosomes for a………………… are XX whereas that for a………………… are XY.

Q 24.

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 25.

Where did life originate on the earth ?

Q 26.

Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species ?

Q 27.

Why are the traits acquired during the lifetime of an individual not inherited ?

Q 28.

(a) What is meant by a species ? Give two examples of plant species and two of animals.
(b) State the various factors which could lead to the formation of new species.

Q 29.

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

Q 30.

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

Q 31.

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

Q 32.

Why are traits acquired during the lifetime of an individual not inherited ?

Q 33.

Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics ?

Q 34.

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

Q 35.

Explain the terms analogous and homologous organs with examples.

Q 36.

Name the plant on which Mendel performed his experiments.

Q 37.

During which stage can the chromosomes be seen clearly? Write the features of the eukaryotic and prokaryotic chromosomes.

Q 38.

Define ‘evolution’. Describe Darwin’s theory of evolution.

Q 39.

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

Q 40.

Describe briefly four ways in which individuals with a particular trait may increase in a population. [Foreign]

Q 41.

What are fossils? What do they tell us about the process of evolution? [All India(C): All India 2011]

Q 42.

Distinguish between acquired and inherited traits by giving one example of each. Why are traits acquired during the lifetime of an individual not inherited? [Delhi(C)]

Q 43.

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 44.

Give one example each of characters that are inherited and the ones that are acquired in humans. Mention the difference between the inherited and the acquired characters. [Delhi]

Q 45.

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

Q 46.

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

Q 47.

What evidence do we have for the origin of life from inanimate matter? [All India]

Q 48.

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

Q 49.

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

Q 50.

Define the term ‘evolution’. “Evolution cannot be equated with progress”. Justify this statement. [Delhi]