Biology

Heredity and Evolution

Question:

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.

Answer:

(a) Genes.
(b) Chromosomes.

previuos
next

Heredity and Evolution

Q 1.

A man having blood group O marries a woman having blood group B and they have a daughter. What will be the blood group of the daughter ?

Q 2.

With the help of an example, explain how variation leads to evolution.

Q 3.

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

Q 4.

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

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.

Mendel said that the characteristics or traits of organisms are carried from one generation to the next by internal factors which occur in pairs. What is the modern name for these factors ?

Q 7.

Which of the two, sperm or ovum, decides the sex of the child ?

Q 8.

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 9.

(a) How do Mendel’s experiments show that traits may be dominant or recessive ?
(b) How do Mendel’s experiments show that traits are inherited independently ?

Q 10.

Name the scientist who gave the theory of evolution.

Q 11.

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 12.

In human beings, the statistical probability of getting either a male or female child is 50 : 50. Give a suitable explanation.

Q 13.

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 14.

What is a retrovirus?

Q 15.

What is a sex chromosome?

Q 16.

Define evolution. Describe the contribution of Lamarck.

Q 17.

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

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.

Which of the processes, sexual reproduction or asexual reproduction, brings about maximum variations in the offsprings ?

Q 20.

What are the chromosomes XY and XX known as ?

Q 21.

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

Q 22.

What type of plants were used by Mendel for conducting his experiments on inheritance ?

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.

a) Name the scientist who gave the laws of inheritance.
(b) Name an animal in which individuals can change sex. What does this indicate ?

Q 25.

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

Q 26.

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

Q 27.

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

Q 28.

What name is given to the sequence of gradual changes over millions of years in which new species are produced ?

Q 29.

State whether the following statement is true or false :
Human beings have evolved from chimpanzees.

Q 30.

Name five varieties of vegetables which have been produced from ‘wild cabbage’ by the process of artificial selection.

Q 31.

In what way are homologous organs evidence for evolution ?

Q 32.

(a) Define ‘natural selection’.
(b) “Only variations that confer an advantage to an individual organism will survive in a population”. Do you agree with this statement ? Give reason for your answer.

Q 33.

Define variation.

Q 34.

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

Q 35.

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 36.

Name the ancestor of the following :
Broccoli, Kohlrabi, Kale

Q 37.

Name the famous book written by Charles Robert Darwin.

Q 38.

Can the wing of a butterfly and the wing of a bat be considered homologous organs ? Why or why not ?

Q 39.

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

Q 40.

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

Q 41.

Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually ? Give reason for your answer.

Q 42.

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

Q 43.

(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 44.

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 45.

What are homologous structures? Give an example. Is it necessary that homologous structures always have a common ancestor?

Q 46.

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

Q 47.

If a 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 48.

What are the different ways in which individuals with a particular trait may increase in a population ?

Q 49.

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

Q 50.

Will geographical isolation be a major factor in the speciation of a self-pollinating plant species ? Why or why not ?