Lakhmir Singh solutions for Biology (Science) [English] Class 10 chapter 4 - Heredity and Evolution [Latest edition]

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

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?

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

Fill in the following blank with suitable word :                  

Genes always work in ................ .

Fill in the following blank with suitable word .

 In pea plants, the gene for dwarfness is ..............whereas that for tallness is ............ .

Fill in the following blank with suitable word .

Most people have ............earlobes but some have ............earlobes.

Fill in the following blank with suitable word :

 A human gamete contains.............. chromosomes whereas a normal body cell has .......... chromosomes in it.

Fill in the following blank with suitable word :

 All races of man have...........blood groups.

Fill in the following blank with suitable word :

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

Name the scientist who gave the laws of inheritance.

Using height (tallness/dwarfness) of a plant as an example, show that genes control the characteristics or traits in an organism.

State one advantage of variation to a species.

Explain how, sex is determined in human babies.

What do the following symbols used in the topic on heredity represent of TT ?

What do the following symbol used in the topic on heredity represent of tt?

What do the following symbol used in the topic on heredity represent of XX ?

What do the following symbol used in the topic on heredity represent of XY ?

 What will you get in the F₁ and F₂ generations in the following cross?
Pure tall pea plant × Pure dwarf pea plant

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.

   What is the genotype of dwarf plants which always produced dwarf offspring?

What is the genotype of tall plants which always produced tall offspring

What is the genotype of (i) dwarf plants, and (ii) tall plants, whose parental cross always produces tall offspring?

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

In a human, how many chromosmes are present in a brain cell?

In a human, how many chromosmes are present in a sperm in the testes?

In a human, how many chromosmes are present in an egg which has just been produced by the ovary?

In a human, how many chromosmes are present in a skin cell?

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 Give the modern name for this 'factor'.
 

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' State where these factors are found in gametes.

Give the contrasting traits of the following characters in pea plant and mention which is dominant and which is recessive:  

Yellow seed

Give the contrasting traits of the following characters in pea plant and mention which is dominant and which is recessive :

 Round seed

Define heredity.

What are the units of heredity.

 Why did Mendel choose pea plants for conducting his experiments on inheritance?

State Mendel's second law of inheritance.

What do you understand by the term variation?

Name two human traits which show variation.

How does the creation of variation in a species ensure its survival

What are genes? Where are the genes located?

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

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

How do Mendel's experiments show that traits may be dominant or recessive?

How do Mendel's experiments show that traits are inherited independently?

When two parents are crossed, the offspring are referred to as :
recessives
 test cross
 F₁ generation
 F₂ generation

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 ______

The human animal which has an XY pair of chromosomes is called :
(a) male
(b) hybrid
(c) female
(d) doomed

The science of heredity is known as :
(a) biology
(b) embryology
(c) genetics
(d) biochemistry

A gene is a :
(a) hybrid
(b) heritable trait
(c) pure breed
(d) part of a chromosome that transmits a trait

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 plant with two 'small' genes breeds with a plant with two 'tall' genes to produce :

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^A I^A and I^B I^O
(b) I^A I^B and I^B I^O
(c) I^A I^O and I^B I^O
(d) I^A I^B and I^A I^O

The palisade cells of a species of plant contain 28 chromosomes. How many chromosomes will there be in each gamete produced by the plant?
(a) 56
(b) 28
(c) 14
(d) 4

Which of the following may be used to obtain an F₂ generation?
(a) allowing flowers on a parent plant to be self-pollinated
(b) allowing flowers on an F₁ plant to be self-pollinated
(c) cross-pollinating an F₁ plant with a parent plant
(d) cross-pollinating two parent plants

The following results were obtained by a scientist who crossed the F₁ generation of pure-breeding parents for round and wrinkled seeds. 

From these results, it can be concluded that the actual number of round seeds he obtained was ______  

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 plant is not governed by gene T or t

The number of pair(s) of sex chromosomes in the zygote of humans is :
(a) one
(b) two
(c) three
(d) four

In peas, a pure tall plant (TT) is crossed with a pure short plant (tt). The ratio of pure tall plants to pure short plants in F₂ generation will be ______.

The two versions of a trait (character) which are brought in by the male and female gametes are situated on :
(a) copies of the same chromosome
(b) sex chromosomes
(c) two different chromosomes
(d) any chromosomes

Select the statements that describe characteristics of genes :
(i) genes are specific sequences of bases in a DNA molecule.
(ii) a gene does not code for proteins.
(iii) in individuals of a given species, a specific gene is located on a particular chromosome.
(iv) each chromosome has only one gene..

Select the group which shares the maximum number of common characters.

A trait in an organism is influenced by ______ 

In human males all the chromosomes are paired perfectly except one. This/these unpaired chromosomes is/are :
(i) large chromosome
(ii) small chromosome
(iii) Y chromosome
(iv) X chromosome

A zygote which has inherited an X chromosome from the father will develop into :
(a) baby boy
(b) baby girl
(c) adult
(d) either boy or girl

Which of the following statement is incorrect?
(a) for every hormone there is a gene
(b) for every protein there is a gene
(c) for production of every enzyme there is a gene
(d) for every type of fat there is a gene

If the ratio of each phenotype of the seeds of pea plants in the F₂ generation is 9 : 3 : 3 : 1, it is known as :
(a) tetrahybrid ratio
(b) monohybrid ratio
(c) dihybrid ratio
(d) trihybrid ratio

In humans, if gene B gives brown eyes and gene b gives blue eyes. What will be the colour of eyes of the persons having the following combination of genes?
(a) Bb
(b) bb
(c) BB

A plant has two varieties, one with red petals and the other with white petals. When these two varieties are cross-pollinated, all the offsprings have red petals?
(a) Which gene is dominant?
(b) Choose suitable letters to represent the two genes.

E is the gene for brown eye colour and an is the gene for blue eye colour. which gene is (1)  recessive, and (2) dominant?

Both father and mother have the genes Ee in their cells. What colour are their eyes?

Which combination of genes in the zygote will produce children with blue eyes?

A couple with a newborn baby is troubled that the child does not resemble either of them. Suspecting that a mixup occurred at the hospital, they check the blood type of the infant. It is type O. Because the father is type A and the mother type B, they conclude that a mixup has definitely occurred. Are they correct? Give reason for your answer.

A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as:

A person first crossed pure-bred pea plants having round-yellow seeds with pure-bred pea plants having wrinkled-green seeds and found that only A-B type of seeds were produced in the F₁ generation. When F₁generation pea plants having A-B type of seeds were cross-bred by self-pollination, then in addition to the original round-yellow and wrinkled-green seeds, two new varieties A-D and C-B type of seeds were also obtained.
(a) What are A-B type of seeds?
(b) State whether A and B are dominant traits or recessive traits.
(c) What are A-D type of seeds?
(d) What are C-B type of seeds?
(c) Out of A-B and A-D types of seeds, which one will be produced in (i) minimum numbers, and (ii) maximum numbers, in the F₂ generation?

The person A has only B chromosomes in all its gametes. On the other hand, another person C has chromosome D in half of gametes and chromosome E in the other half of gametes. When chromosomes B and D combine during fertilisation, a female zygote results. On the other hand, combination of B and E chromosomes produces a male zygote.
(a) What are chromosomes (i) B (ii) D, and (iii) E?
(b) Out of B, D and E, which two chromosomes are of the same type?
(c) Which chromosome is smaller in size?
(d) What is the general name of chromosomes such as B and E?
(e) Out of the two persons A and C, which one is (i) male, and (ii) female?

Mendel first crossed pure-bred pea plants having round-yellow seeds with pure-bred pea plants having wrinkled-green seeds and found that only round-yellow seeds were produced in the F₁ generation. When F₁generation pea plants having round-yellow seeds were cross-bred by self pollination, then peas having round-yellow seeds, round green seeds, wrinkled-yellow seeds and wrinkled-green seeds were produced. Mendel collected a total of 2160 seeds.
(a) What will be the number of (i) round green seeds (ii) wrinkled green seeds (iii) round yellow seeds, and (iv) wrinkled-yellow seeds?
(b) Which 'ratio' as established by Mendel have you made use of in answering the part (a) above?

Pure-bred round-yellow pea seeds have genotype RRYY and the pure-bred wrinkled-green pea seeds have genotype rryy. Keeping this in mind, write the phenotypes of the following genotypes of hybrid pea seeds :
(a) Rryy
(b) rrYy
(c) rrYY
(d) RrYy
(e) RRyy

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

Name an animal having rudimentary eyes.

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

^{Where did life originate on the earth?}

Write the names of at least three inorganic molecules which helped in the origin of life on the earth.

Name the famous book written by Charles Robert Darwin.

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

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

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

Choose the one term from the following which includes the other three :
broccoli, wild cabbage, cauliflower, cabbage

Fill in the following blank with suitable word :

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.

Fill in the following blank with suitable word :

 The evolution of eye is an example of evolution by ............

Fill in the following blank with suitable word :

The scientific name of all human beings is ..............

Fill in the following blank with suitable word:

 Broccoli has evolved from .............. by the process of artificial selection.

Fill in the following blank with suitable word :

The theory of natural selection for evolution was proposed by ..............

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

What is meant by acquired and inherited traits? Explain with one example each.

Why are traits acquired during the life-time of an individual not inherited?

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

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

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

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

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

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

Give two examples of plant species and two of animals.

What is meant by a species? 

 State the various factors which could lead to the formation of new species.

Does geographical isolation of individuals of a species lead to the formation of a new species? Provide a suitable explanation for your answer.

Name the scientist who gave the theory of origin of life on earth. What is this theory?

State Darwin's theory of evolution.

What do you understand by the term 'evolution'?

Explain the terms 'analogous organs' and 'homologous organs' with examples.

In what way are analogous organs evidence for evolution?

Define 'speciation'. Explain how speciation occurs.

"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.

 Will geographical isolation be a major factor in the speciation of a self-pollinating plant species? Give reason for your answer.

Define 'natural selection'.

 In evolutionary terms, we have more in common with

The human species has genetic roots in ______

A gradual change, over a long period, in a form of life is known as :
(a) erosion
(b) evolution
(c) revolution
(d) evaluation

Scientists believe that all life originated in :
(a) the sea
(b) the soil
(c) the ground
(d) the air

The theory of evolution of species by natural selection was given by ______ 

The term 'father of genetics' is used for the scientist :
(a) Morgan
(b) Mendel
(c) Darwin
(d) Marie Curie

One of the following traits cannot be inherited. This one is :
(a) colour of eyes
(b) colour of skin
(c) size of body
(d) nature of hair

Only one of the following characteristic of the parents can be inherited by their children. This one is :
(a) deep scar on chin
(b) snub nose
(c) technique of swimming
(d) cut nose

The organs which perform different functions but have the same basic structure are known as :
(a) homologous organs
(b) analogous organs
(c) homolytic organs
(d) analytic organs

The organs which perform similar functions but have different basic structure are called :
(a) asymmetric organs
(b) analogous organs
(c) homologous organs
(d) homophonic organs

Wing of an insect and forelimb of a bird are :
(a) analogous organs
(b) analeptic organs
(c) homologous
(d) homophobic organs

If the fossil of an organism is found in the deeper layers of earth, then we can predict that ______ 

Which of the following statement is incorrect with respect to variations?
(a) all variations in a species have equal chance of survival
(b) change in genetic composition results in variations
(c) selection of variations by environmental factors forms the basis of evolutionary process
(d) variations are the minimum in asexual reproduction

One of the following traits of the parents cannot be passed on to their future generations. This trait is :
(a) cleft chin
(b) pointed chin
(c) scarred chin
(d) broad chin

Select the incorrect statement from the following :
(a) frequency of certain genes in a population changes over several generations resulting in        evolution
(b) reduction in the weight of an organism due to starvation is genetically controlled
(c) low weight parents can have heavy weight progeny
(d) traits which are not inherited over generations do not cause evolution.

New species may be formed if:

1. DNA undergoes significant changes in germ cells
2. chromosome number changes in the gamete
3. there is no change in the genetic material
4. mating does not take place

According to the evolutionary theory, the formation of a new species is generally due to ______

The presence of which of the following types of organs in two animals indicates that they are not derived from a common ancestor?
(a) homologous organs
(b) excretory organs
(c) analogous organs
(d) reproductive organs

The presence of which of the following types of organs in two organisms indicates that they are derived from the same ancestor?
(a) analogous organs
(b) respiratory organs
(c) digestive organs
(d) homologous organs

One of the following has not been produced from wild cabbage by the process of artificial selection. This one is :
(a) kohlrabi
(b) cabbage
(c) spinach
(d) kale

The fossil trilobite was originally :
(a) an arthropod
(b) an invertebrate
(c) a reptile
(d) an ave

One pair of organs in the following animals are not homologous. This is :
(a) forelimbs in humans and lizard
(b) forelimbs in lizard and frog
(c) wings in butterfly and bat
(d) wings in bat and bird

 The wings of a housefly and the wings of a sparrow are an example of :
(a) analogous organs
(b) vestigial organs
(c) respiratory organs
(d) homologous organs

Some of the important fossils which have been studied are those of organisms X, Y and Z. X were marine arthropods which were common between 400 to 600 million years ago. Y were the invertebrate animals (molluscs) with a flat, coiled, spiral shell which lived in the sea about 180 million years ago. Z are the extinct carnivorous or herbivorous reptiles which appeared on the earth about 250 million years ago and became extinct about 65 million years ago. What are X, Y and Z?

The farmers have been cultivating a food plant X for over two thousand years and have produced as many as five entirely different looking vegetables A, B, C, D and E from it.
(a) What could the plant X be?
(b) What are A, B, C, D and E?
(c) What is the process of evolution involved in this example known as?

There are five animals A, B, C, D and E. The animal A uses its modified forelimbs for flying. The animal B uses its forelimbs for running whereas the animal C uses its forelimbs for grasping. The animal D can live on land as well as in water and uses its forelimbs to prop up the front end of its body when at rest. The animal E which respires by using spiracles and tracheae uses wings for flying but its wings are analogous to the modified forelimbs of animal A.
(a) What could the animals A, B, C, D and E be?
(b) Why are the forelimbs of animals A, B, C, D called homologous organs?
(c) What does the existence of homologous organs in animals A, B, C and D tell us about their ancestors ?
(d) Why are the modified forelimbs of animal A and the wings of animal E called analogous organs?
(e) State whether animals A and E have a common ancestor or not.

X, Y, and Z are three animals. The animal X can fly but animal Y can only run on ground or walls. The forelimbs of animals X and Y have the same basic design but they are used for different purposes such as flying and running respectively. The animal Z became extinct an long time ago. The study of fossils of Z tells us that it had some features like those of X and some like those of Y. In fact, Z is said to form a connecting link in the evolutionary chain of X and Y.
(a) What could the animals X, Y and Z be?
(b) What name is given to the forelimbs like those of X and Y which have the same basic design but different functions?
(c) Name one feature in which Z resembled X.
(d) Name one feature in which Z resembled Y.
(e) Which is the correct evolutionary chain involving X, Y and Z : X → Z → Y or Y → Z → X?

A population of red beetles lives in green bushes in a garden. Once during the process of breeding, a green beetle is produced.
(a) State whether the change in colour of beetle is a process of evolution or not.
(b) Can the new colour of green beetle be passed on to its next generations?
(c) What will be the advantage (if any) of the green colour to the beetle?
(d) State whether the production of green colour involved a change in genetic material or not.

The organs P and Q of two animals have different structures but similar functions. On the other hand, the two organs R and S of two other animals have the same basic structure but different functions.
(a) What are the organs like P and Q known as?
(b) Name the organs like P and Q. Also name the animals which have such organs.
(c) What are the organs like R and S called?
(d) Name the organs like R and S. Also name the animals which have such organs.