Question

The sequence of gradual changes which takes place in the primitive organisms over millions of years in which new species are produced is known as *

1 point

Evolution

Heredity

Generation

Inheritance

​

Answer 1

Answer:

Evolution is the sequence of gradual changes which take place in the primitive organisms over millions of years in which new species are produced. Since, we are talking about living organisms, so it is known as 'organic evolution'.

Answer 2

Answer:

Question 1:

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

Solution :

Sexual Reproduction

Question 2:

Name one variation in humans connected with ears.

Solution :

Free Earlobes.

Question 3:

What constitutes the link between one generation and the next ?

Solution :

Gametes.

Question 4:

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 ?

Solution :

B.

Question 5:

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 ?

Solution :

Genes.

Question 6:

Some plants occur in one of the two sizes : tall or dwarf. This characteristic is controlled by one pair of genes. Tallness is dominant to dwarfness. Choose suitable letters for this gene pair.

Solution :

Tt.

Question 7:

What are the chromosomes XY and XX known as ?

Solution :

Sex Chromosomes.

Question 8:

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

Solution :

Sperm.

Question 9:

State whether the following statement is true or false :

The sex of an infant is not a case of inheritance of characteristics.

Solution :

False.

Question 10:

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

Solution :

Baby boy

Question 11:

Which of the following combinations of sex chromosomes produce a male child : XX or XY ?

Solution :

XY.

Question 12:

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

Solution :

Gregor Mendel

Question 13:

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

Solution :

Pea plants.

Question 14:

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 ?

Solution :

Black hair.

Question 15:

What are the four blood groups in humans ?

Solution :

A, B, AB and O.

Question 16:

Name one reptile in each case where higher incubation temperature leads to the development of : (a) male progeny, (b) female progeny.

Solution :

(a) Lizard (Agama agama)

(b) Turtle (Chrysema Picta)

Question 17:

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.

Solution :

(a) Pairs.

(b) Recessive; Dominant.

(c) Free; attached.

(d) 23; 46.

(e) Four.

(f) Sex; Female; male.

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