Science for class tenth - Subject-Biology solutions for Chapter 4 Heredity and Evolution

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

Name one variation in humans connected with ears.

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?

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.

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

State whether the following statement is true or false:

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

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

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

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

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.

Which of the following represent tall plants and which represent short plants (or dwarf plants)?

(a) Tt

(b) tt

(c) TT

Give a reason for your choice (The symbols have their usual meaning).

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?

(a) State one advantage of variation to a species. (b) What are sex chromosomes? How many sex chromosomes are there? Name them.

What do the following symbols use in the topic on heredity represent?

(a) TT

(b) tt

(c) XX

(d) XY

In the F2 generation of a cross, progeny having different traits are produced in the ratio 3:1. State whether it is a monohybrid cross or a dihybrid cross? Give one example of such a cross.

(a) If a normal human cell has 46 chromosomes, how many chromosomes will be there in a human (i) sperm cell, and (ii) zygote?

(b) What sizes of plants are produced if both parents have genes Tt?

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.

(a) What is meant by 'heredity'? What are the units of heredity?

(b) State Mendel's first law of inheritance.

(a) What do you understand by the term 'variation'?

(b) Name two human traits which show variation.

(c) How does the creation of variation in a species ensure its survival?

(a) What are genes? Where are they located in our body?

(b) What is meant by dominant genes and recessive genes? Give one example of each.

(c) Explain how characteristics (or traits) are inherited through genes.

(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?

A cross between two individuals results in a ratio of 9 : 3 : 3 : 1 for four possible phenotypes of progeny. This is an example of a :

(a) dihybrid cross

(b) monohybrid cross

(c) test cross

(d) none of these

For his experiments on heredity, Mendel used:

(a) papaya plants

(b) potato plants

(c) pea plants

(d) pear plants

The science of heredity is known as:

(a) biology

(b) embryology

(c) genetics

(d) biochemistry

In order to ensure that he had pure-breeding plants for his experiments, Mendel :

(a) cross-fertilized each variety with each other

(b) let each variety self-fertilize for several generations

(c) removed the female parts of the plants

(d) removed the male parts of the plants

In the human blood grouping, the four basic blood types are type A, type B, type AB, and type O. The blood proteins A and B are:

(a) simple dominant and recessive traits

(b) incomplete dominant traits

(c) codominant traits

(d) sex-linked traits

A pregnant woman has an equal chance of her baby being blood group A or blood group AB. Which one of the following shows the possible genotypes of the woman and the father of her child?

(a) $I^AI^A\ and\ \ I^BI^O$

(b) $I^AI^B\ \ and\ I^BI^O$

(c) $I^AI^O\ and\ I^BI^O$

(d) $I^AI^B\ and\ I^AI^O$

The visible characteristic in an organism is known as:

(a) prototype

(b) stereotype

(c) phenotype

(d) genotype

The exchange of genetic material takes place in:

(a) vegetative reproduction

(b) asexual reproduction

(c) sexual reproduction

(d) budding

A cross between a tall plant (TT) and short plant (tt) resulted in progeny that were all tall plants because :

(a) tallness is the dominant trait

(b) shortness is the dominant trait

(c) tallness is the recessive trait

(d) height of the plant is not governed by gene T or t

A trait in an organism is influenced by:

(a) paternal DNA only

(b) maternal DNA only

(c) both maternal and paternal DNA

(d) neither by paternal nor by maternal DNA

The sex of a child is determined by which of the following?

(a) the length of the mother's pregnancy

(b) the length of time between ovulation and copulation

(c) the presence of an X chromosome in an ovum

(d) the presence of a Y chromosome in a sperm

Science for class tenth subject biology Solutions for Chapter 4 heredity and evolution