Principles Of Inheritance

Question 1

Gregor Mendel, conducted hybridisation experiments on garden peas for……….and proposed the laws of inheritance in living organisms

Answer 1

seven years
(1856-1863)

Question 2

Assertion: Mendel experiment had large credibility to the data that he collected
Reason: His experiments had a large sampling size

Answer 2

Both are correct and correct explanation

Question 3

Statement 1: A true-breeding line is one that, having undergone continuous self-pollination, shows the stable trait inheritance and expression for several generations
Statement 2: Mendel selected 14 true-breeding pea plant varieties, as pairs which were similar except for one character with contrasting traits.

Answer 3

Both are correct

Question 4

It was developed by a British geneticist, Reginald C. Punnett.

Answer 4

Punnett square

Question 5

The inheritance of flower colour in the dog flower (snapdragon or Antirrhinum sp.) is a good example to understand………

Answer 5

incomplete dominance

Question 6

Mendel published his work on inheritance of characters in……..

Answer 6

1865

Question 7

Reasons for failure of Mendel’s work

Answer 7

Firstly, communication was not easy (as it is now) in those days and his work could not be widely publicised.

Secondly, his concept of genes as stable and discrete units that controlled the expression of traits and, of the pair of alleles which did not ‘blend’ with each other, was not accepted by his contemporaries as an explanation for the apparently continuous variation seen in nature.

Thirdly, Mendel’s approach of using mathematics to explain biological phenomena was totally new and unacceptable to many of the biologists of his time.

Finally, though Mendel’s work suggested that factors (genes) were discrete units, he could not provide any physical proof for the existence of factors or say what they were made of.

Question 8

Statement 1: By 1905 the chromosome movement during meiosis had been worked out.
Statement 2: Walter Sutton and Theodore Boveri noted that the behaviour of chromosomes was parallel to the behaviour of genes and used chromosome movement to explain Mendel’s laws

Answer 8

Statement 1 is false and 2 is true

In year 1902 chromosome movement…………

Question 9

Independent pairs segregate independently of each other this refers to……

Answer 9

Gene

Question 10

One pair segregates independently of another pair it refers to………

Answer 10

Chromosome

Question 11

Morgan worked with the tiny fruit flies, Drosophila melanogaster (which were found very suitable for such studies.
Why?

Answer 11

1. They could be grown on simple synthetic medium in the laboratory. 2. They complete their life cycle in about two weeks [14-15 days] and a single mating could produce a large number of progeny flies.
2. There was a clear differentiation of the sexes – the male and female flies are easily distinguishable.
3. It has many types of hereditary variations that can be seen with low power microscopes.

Question 12

Morgan hybridised
females to
males

Answer 12

Females; yellow-bodied, white-eyed
Males: brown-bodied, red-eyed

Question 13

Genes for white and yellow were very tightly linked and showed only ………… percent recombination while white and miniature wing showed…………per cent recombination.

Answer 13

1.3 percent

37.2 percent

Question 14

Cancer cells commonly show chromosomal aberration

Answer 14

True

Question 15

Law of dominance

Answer 15

(I) Characters are controlled by discrete units called factors.
(ii) Factors occur in pairs.
(iii) In a dissimilar pair of factors one member of the pair dominates (dominant) the other (recessive)

Question 16

This subject deals with the inheritance, as well as the variation of characters from parents to offspring.

Answer 16

Genetics

Question 17

………….. is the process by which characters are passed on from parent to progeny; it is the basis of……..

Answer 17

Inheritance

heredity

Question 18

Humans knew from as early as………… that one of the causes of variation was hidden in sexual reproduction.

Answer 18

8000-1000 B.C.

Question 19

Gregor Mendel, conducted hybridisation experiments on garden peas for seven years………………. and proposed the laws of inheritance in living organisms

Answer 19

1856-1863

Question 20

Assertion: There was greater credibility to the data that he collected
Reason: His experiments had a large sampling size

Answer 20

Both are correct and correct explanation

Question 21

Statement 1: A true-breeding line is one that, having undergone continuous self-pollination, shows the stable trait inheritance and expression for several generations
Statement 2: Mendel selected 14 true-breeding pea plant varieties, as pairs which were similar except for one character with contrasting traits.

Answer 21

Both are correct

Question 22

Based on his observations, Mendel proposed that something was being stably passed down, unchanged, from parent to offspring through the gametes, over successive generations. He called these things as……

Answer 22

factors

Question 23

Genes which code for a pair of contrasting traits are known as……….i.e., they are slightly different forms of the same gene.

Answer 23

alleles

Question 24

Based on his observations on…………crosses Mendel proposed two general rules to consolidate his understanding of inheritance in these crosses

Answer 24

monohybrid

Question 25

Law of ………… states alleles do not show any blending and that both the characters are recovered as such in the F2 generation

Answer 25

Segregation Though the parents contain two alleles during gamete formation, the factors or alleles of a pair segregate from each other such that a gamete receives only one of the two factors

Question 26

When experiments on peas were repeated using other traits in other plants, it was found that sometimes the F1 had a phenotype that did not resemble either of the two parents and was in between the two. True or false

Answer 26

True

Question 27

Assertion: IA and IB are completely dominant over i, in other words when IA and i are present only IA expresses

Answer 27

Reason: i does not produce any sugar

Question 28

Human ABO blood grouping number of genotypes possible is…….. and number of phenotypes is………

Answer 28

6 genotypes 4 phenotypes

Question 29

Starch synthesis in pea seeds show some tinge of incomplete dominance

Answer 29

BB= Effective starch synthesis and large starch grains round seeds Bb= Round seeds but of intermediate size bb= Low efficiency and smaller starch grains with wrinkled seed

Question 30

By……….the chromosome movement during meiosis had been worked out

Answer 30

1902

Question 31

Two scientists………….. & …………… noted that the behaviour of chromosomes was parallel to the behaviour of genes and used chromosome movement to explain Mendel’s laws

Answer 31

Walter Sutton and Theodore Boveri

Question 32

Independent pairs segregate independently of each other Is for genes or chromosomes?

Answer 32

Genes Genes here specifically referred as independent pairs as there can be two kind of genes which are inherited independently or not. Those that show high tendency of recombination are inherited independently by nature but those showing linkages show low recombination and have tendency to be inherited together. Here the independent word is significant as only those are segregated independently of each other

Question 33

One pair segregates independently of another pair Is for genes or chromosomes?

Answer 33

Chromosomes

Question 34

Statement 1: Sutton and Boveri argued that the pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried Statement 2: Boveri united the knowledge of chromosomal segregation with Mendelian principles and called it the chromosomal theory of inheritance.

Answer 34

Statement 1 is correct and 2 is incorrect Sutton was the one who united the theory If in options both given together then mark it and if both given separately then mark for Sutton

Question 35

The experimental verification of the chromosomal theory of inheritance by………… and his colleagues, led to discovering the basis for the variation that sexual reproduction produced

Answer 35

Thomas Hunt Morgan (Flyman of genetics)

Question 36

Drosophila melanogaster were found very suitable for such studies Why (5)

Answer 36

Grown on simple synthetic medium in the laboratory They complete their life cycle in about two weeks A single mating could produce a large number of progeny flies There was a clear differentiation of the sexes – the male and female It has many types of hereditary variations that can be seen with low power microscopes.

Question 37

Morgan carried out several……….crosses in Drosophila to study genes that were sex-linked.

Answer 37

dihybrid

Question 38

Morgan hybridised………..&………… females to………..&………..males and intercrossed their F1 progeny

Answer 38

yellow-bodied, white-eyed brown-bodied, red-eyed

Question 39

Statement 1: When the two genes in a dihybrid cross were situated on the same chromosome, the proportion of parental gene combinations were much higher than the non-parental type. Statement 2; Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage to describe this physical association of genes on a chromosome

Answer 39

Both are correct

Question 40

Morgan and his group also found that even when genes were grouped on the same chromosome, some genes were very tightly linked (showed very low recombination) while others were loosely linked (showed higher recombination)

Answer 40

True

Question 41

The genes white and yellow were very tightly linked and showed only…………..per cent recombination while white and miniature wing showed……….per cent recombination.

Answer 41

1.3% 37.2%

Question 42

…………….. student of Morgan used the frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes and ‘mapped’ their position on the chromosome.

Answer 42

Alfred Sturtevant

Question 43

Statement 1:Some traits are generally controlled by three or more genes and are thus called as polygenic traits. Statement 2: Polygenic inheritance doesn’t take into account the influence of environment

Answer 43

Statement 1 is correct but 2 is incorrect Besides the involvement of multiple genes polygenic inheritance also takes into account the influence of environment

Question 44

Statement 1: When single gene can exhibit multiple phenotypic expression such a gene is called a pleiotropic gene. Statement 2: The underlying mechanism of pleiotropy in most cases is the effect of a gene on metabolic pathways which contribute towards different phenotypes

Answer 44

Both are correct

Question 45

Henking in year……….. could trace a specific nuclear structure all through spermatogenesis in a few insects, and it was also observed by him that 50 per cent of the sperm received this structure after spermatogenesis, whereas the other 50 per cent sperm did not receive it.

Answer 45

1891 Henking gave a name to this structure as the X body but he could not explain its significance.

Question 46

It is also evident that in each pregnancy there is always per cent probability of either a male or a female child

Answer 46

50%

Question 47

Chromosomal aberrations are commonly observed in……..cells.

Answer 47

cancer

Question 48

Some mutation also arise due to change in a single base pair of DNA. This is known as………

Answer 48

point mutation

Question 49

………… radiations can cause mutations in organisms – it is a mutagen.

Answer 49

UV

Question 50

Colour blindness is a sex-linked (on X chromosome) ………… disorder due to defect in either……. or……….. colour cone of eye resulting in failure to discriminate between these colours

Answer 50

recessive red or green

Question 51

Colour blindness occurs in about………per cent of males and only about…….. per cent of females.

Answer 51

8% 0.4%

Question 52

Haemophilia is sex linked………….. disease. In this disease…………protein that is a part of the cascade of proteins involved in the clotting of blood is affected

Answer 52

recessive a single protein

Question 53

Assertion: The possibility of a female becoming a haemophilic is extremely rare Reason: mother of such a female has to be at least carrier and the father should be haemophilic (unviable in the later stage of life)

Answer 53

Both are correct and correct explanation

Question 54

The family pedigree of Queen Victoria shows a number of haemophilic descendents as she was………….. the disease.

Answer 54

a carrier of the disease

Question 55

Sickle-cell anaemia is …………… linked recessive trait that can be transmitted from parents to the offspring when both the partners are carrier for the gene (or heterozygous).

Answer 55

autosome linked

Question 56

Sickle cell anemia is caused by the substitution of……… by ………… at the……….. position of the………. globin chain of the haemoglobin molecule.

Answer 56

Glutamic acid (Glu) by Valine (Val) sixth beta

Question 57

Codon changes in sickle cell anemia

Answer 57

Normally DNA …GAG… …CTC… mRNA …GAG…. Abnormal DNA …GTG… …CAC… mRNA …GUG…

Question 58

This inborn error of metabolism is also inherited as the autosomal recessive trait

Answer 58

Phenylketonuria

Question 59

In phenylketonuria individual lacks an enzyme "phenylalanine hydroxylase" that converts the amino acid phenylalanine into…..

Answer 59

tyrosine

Question 60

Statement 1: Accumulation of phenylalanine and its derivatives in brain results in mental retardation. Statement 2: These are also excreted through urine because of its poor absorption by kidney.

Answer 60

Both are correct

Question 61

Thalassemia………… linked recessive blood disease transmitted from parents to the offspring when both the partners are unaffected carrier for the gene

Answer 61

autosome linked

Question 62

Alpha Thalassemia is controlled by two closely linked genes…….. and ………… on chromosome……….. of each parent and it is observed due to mutation or deletion of one or more of the four genes.

Answer 62

HBA1 and HBA2 16

Question 63

Beta Thalassemia is controlled by a single gene……..on chromosome……..of each parent and occurs due to mutation of one or both the genes.

Answer 63

HBB 11

Question 64

Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s) called

Answer 64

aneuploidy

Question 65

Failure of cytokinesis after telophase stage of cell division results in an increase in a whole set of chromosomes in an organism and, this phenomenon is known as………This condition is often seen in……

Answer 65

polyploidy plants