Genetics

Question 1

define genetics

Answer 1

genetic is the study of heredity/ transmission of body features (both similarities and differences) from parents to offspring and the laws relating to such transmission

Question 2

define heredity

Answer 2

transmission of genetically based characteristics from parents to offspring

Question 3

define variations

Answer 3

small differences among the individuals of the same species

Question 4

define characters

Answer 4

any inheritable feature of an organism

Question 5

define traits

Answer 5

alternative forms of characters

Question 6

what is karyotype

Answer 6

a chart where photographs of chromosomes are used for artificially arranging the chromosomes according to their size and shape on a chart.

Question 7

define homologous chromosomes

Answer 7

a pair of corresponding chromosomes of the same shape, size, one obtained from each parent

Question 8

what do autosomes determine (autosomes)

Answer 8

general body features like complexion, height, seed colour

Question 9

what do sex chromosomes (allosomes) determine

Answer 9

sex of organism

Question 10

define genes

Answer 10

specific parts/ DNA segments of a chromosome, which determine the hereditary characteristics

Question 11

define genomes

Answer 11

full complement of DNA (including all genes and intergenic regions) of an organism

Question 12

define alleles

Answer 12

alternative forms of a gene, occupying the same position on homologous chromosome and affecting the same characteristic but in different ways.

Question 13

define dominant allele

Answer 13

the kind of allele which expresses itself regardless of the presence of other alleles for a given gene

Question 14

define recessive allele

Answer 14

the kind of allele whose expression is suppressed by the presence of another dominant allele for a given gene. a recessive allele can express itself only in the presence of another recessive allele

Question 15

define genotype

Answer 15

the set of genes present in the cells of an organism

Question 16

define phenotype

Answer 16

the observable characteristics which are genetically controlled

Question 17

define sex-linked inheritance

Answer 17

appearance of a trait which is due to the presence of an allele exclusively either on the X or Y chromosome.

Question 18

example of X linked inheritance

Answer 18

haemophilia and colour-blindness

Question 19

define monohybrid ratio

Answer 19

the ratio obtained by crossing for two different traits of a single character (phenotypic and genotypic ratio)

Question 20

5 generalised principle based on breeding experiments are

Answer 20

1. each pair of contrasting character depends on genes
2. each individual carries such genes in duplicate
3. an individual produces gametes which have only one member of a pair of genes
4. fertilization of gametes restores duplicate condition of the genes
5. sex cells with respect to the genes they contain, get fertilised at random

Question 21

define dihybrid ratio

Answer 21

gives us the breeding results with two pairs of contrasting characters

Question 22

Mendel’s laws of inheritance

Answer 22

1. law of dominance
2. law of segregation
3. law of independent assortment

Question 23

law of dominance

Answer 23

out of a pair of contrasting characters present together, only one is able to express itself while the other remains suppressed

Question 24

law of segregation/ purity of gametes

Answer 24

two members of a pair of factors separate at the time of formation of gametes

Question 25

law of independent assortment

Answer 25

when there are two pairs of characters, the distribution of alleles of one character into a gamete is independent of the distribution of the alleles of the other character

seen in F1 hybrid in dihybrid cross

Question 26

application of Mendel’s laws

Answer 26

1. knowledge of the basic Mendelian principles gives us an idea of new progeny and enables us to predict their frequency
2. useful info for plant and animal breeders who want to produce better breeds
3. new types of plants with new combination of useful characters can be produced by hybridisation

Question 27

define mutation

Answer 27

mutation is the sudden change in one or more genes, or in the number or in the structure of chromosomes

Question 28

examples of mutation

Answer 28

1. sickle cell anaemia(forms sickle-shaped RBCs)
2. radioactive radiations