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

Name one variation in humans connected with ears.

What constitutes the link between one generation and the next?

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 modem 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.

What are the chromosomes XY and XX known as?

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

State whether the following statement is true or false:

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

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

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

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

The gene for red hair is recessive to the gene for black hair. What will be the hair color of a person if he inherits a gene for red hair from his mother and a gene for black hair from his father ?

What are the four blood groups in humans?

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

A man having blood group 0 marries a woman having blood group B and they have a daughter. What will be the blood group of the daughter?

Name the scientist who gave the laws of inheritance.

Name an animal in which individuals can change sex. What does this indicate?

Explain with an example, how genes control the characteristics (or traits).

State one advantage of variation to a species.

What are sex chromosomes? How many sex chromosomes are there? Name them.

Explain how, sex is determined in human babies.

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

(a) TT (b) tt

(c) XX (d) XY

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

Is it an example of monohybrid cross or dihybrid cross?

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?

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

In a human, how many chromosomes 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 fertilized egg ?

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 modem name for this 'factor'.

(b) State where these factors are found in gametes.

Does genetic combination of mother play a significant role in determining the sex of a new born baby?

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

What is meant by 'heredity' ? What are the units of heredity?

State Mendel's first law of inheritance.

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?

(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.

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 :

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;

For his experiments on heredity, Mendel used:

The human animal which has an XY pair of chromosomes is called:

The science of heredity is known as:

A gene is a:

A normal cell of human body contains 23 pairs of chromosomes. The number of chromosomes in a sex cell

(Sperm or ovum) of a human being is most likely to be:

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

In the human blood grouping, the four basic blood types are type A, type B, type AB, and type 0. The blood proteins A and B are:

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?

The palisade cells of a species of plant contain 28 chromosomes. How many chromosomes will there be in each gamete produced by the plant?

Which of the following may be used to obtain an F₂ generation?

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

Dominant trait -Round seeds

Recessive trait -Wrinkled seeds

No. of F₂ offspring -7524

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:

The exchange of genetic material takes place in:

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

The number of pair(s) of sex chromosomes in the zygote of humans is:

In peas, a pure tall plant (IT) 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:

Select the statements that describe characteristics of genes:

(i) genes are specific sequence 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 chromosome is/are:

(i) Large chromosome

(ii) Small chromosome

(iii) Y chromosome

(iv) X chromosome

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

A zygote which has inherited an X chromosome from the father will develop into :

Which of the following statement is incorrect?

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 :

In humans, if gene B gives brown eyes and gene b gives blue eyes. What will be the color of eyes of the persons having the following combination of genes?

(a) Bb (b) bb (c) BB

Pure-bred pea plants A are crossed with pure-bred pea plants B. It is found that the plants which look like A do not appear in F₁ generation but re-emerge in F₂ generation. Which of the plants A and B are : (i) tall, and (ii) dwarf? Give reason for your answer.

Pure-bred tall pea plants are first crossed with pure-bred dwarf pea plants. The pea plants obtained in F₁ generation are then cross-bred to produce F₂ generation of pea plants.

(a) What do the plants of F₁ generation look like ?

(b) What is the ratio of tall plants to dwarf plants in F₂ generation?

(c) Which type of plants were missing in F₁ generation but reappeared in F₂ generation?

A plant has two varieties, one with red petals and the other with white petals. When these two varieties are cross-pollinated, all the offspring have red petals?

(a) Which gene is dominant?

(b) Choose suitable letters to represent the two genes.

A red-haired woman marries a brown-haired man, and all the children are brown haired. Explain this genetically.

A black mouse mates with a brown mouse, and all the offspring are black.

(a) Why are no brown off springs produced?

(b) If two of the black offspring mate with each other what kind of offspring would you expect and in what proportions? Give reason for your answer.

(a) E is the gene for brown eye color and e is the gene for blue eye color. Which gene is

(i) Recessive, and

(ii) Dominant

(b) Both father and mother have the genes Ee in their cells. What color are their eyes?

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

(d) Which combinations of genes in the zygote will produce children with brown eyes?

What are the possible blood groups likely to be inherited by children born to a group A mother and a group B father? Explain your reasoning.

A couple with a newborn baby is troubled that the child does not resemble either of them. Suspecting that a mix-up occurred at the hospital, they check the blood type of the infant. It is type 0. Because the father is type A and the mother type B, they conclude that a mix-up has definitely occurred. Are they correct? Give reason for your answer

A man with blood group A marries a woman with blood group 0 and their daughter has blood group 0. Is this information enough to tell you which of the traits - blood group A or 0 -is dominant? Why or why not?

A Mendelian experiment consisted of breeding tall TT pea plants bearing violet flowers with short t pea plants bearing white w flowers. The progeny all bore violet W flowers, but almost half of them were short. This suggested that the genetic make-up (or genotype) of the tall parent can be depicted as:

(a) TTWW

(b) TTww

(c) TtWW

(d) TtWw

Give reason for your choice

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 F₁generation. When F₁ generation 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?

(e) 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 fertilization, 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 F₁ generation 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

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

Name the scientist who gave the theory of evolution.

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

State one characteristic which shows that birds are very closely related to dinosaurs.

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.

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?

Name two organisms which are now extinct and studied from their fossils.

Out of the wing of a bird, wing of an insect and the wing of a bat:

(a) Which two are homologous organs?

(b) Which two are analogous organs?

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

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

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

Fill in the following blanks with suitable words:

(a) The human forelimb and bat's forelimb are examples of..................... organs whereas an insect's wing and a bat's wing are an example of ..................... organs.

(b) The evolution of eye is an example of evolution by .....................

(c) The scientific name of all human beings is....................

(d) Broccoli has evolved from ..................... by the process of artificial selection.

(e) 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 the 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?

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

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

Give an example of characteristics being used to determine how close two species are in evolutionary terms.

In what way is homologous organs 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?

Give reason for your answer.

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.

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

What is meant by a species ? Give two examples of plant species and two of animals.

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

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

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

Bacteria have a simpler body plan when compared with human beings. Does it mean that human beings are more evolved than bacteria? Explain your answer.

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

How are those species which are now 'extinct’ studied?

What do you understand by the term 'evolution'? State Darwin's theory of evolution.

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

In what way is analogous organ evidence for evolution?

Define 'speciation'. Explain how speciation occurs.

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

Define 'natural selection'.

"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.

In evolutionary terms, we have more in common with:

The human species has genetic roots in:

Which of the following gas was not present in early earth atmosphere?

A gradual change, over a long period, in a form of life is known as :

Scientists believe that all life originated in:

According to scientists, aves have evolved from:

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

The term 'father of genetics' is used for the scientist:

One of the following traits cannot be inherited. This one is:

Only one of the following characteristic of the parents can be inherited by their children. This one is:

The organs which perform different functions but have the same basic structure are known as:

The organs which perform similar functions but have different basic structure are called:

Wing of an insect and forelimb of a bird are:

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?

One of the following traits of the parents cannot be passed on to their future generations. This trait is:

Some dinosaurs had feathers although they could not fly but birds have feathers that help them to fly. In the context of evolution, this means that:

Select the incorrect statement from the following:

New species may be formed if:

(i) DNA undergoes significant changes in germ cells

(ii) Chromosome number changes in the gamete

(iii) There is no change in the genetic material

(iv) Mating does not take place

According to the evolutionary theory, 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?

The presence of which of the following types of organs in two organisms indicates that they are derived from the same ancestor?

One of the following has not been produced from wild cabbage by the process of artificial selection. This one is:

The fossil trilobite was originally:

One pair of organs in the following animals is 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:

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 and 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 a 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 YZ 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 color of beetle is a process of evolution or not.

(b) Can the new color of green beetle be passed on to its next generations?

(c) What will be the advantage (if any) of the green color to the beetle?

(d) State whether the production of green color 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.