Heredity-2

Question 1

define heredity

Answer 1

Heredity is the mechanism by which genetic characteristics and differences are passed down from one generation to the next.

Question 2

what are acquired and inherited traits

Answer 2

Acquired traits are those which are acquired by an organism after his birth in response to the environment and other influences and cannot be inherited. Also change in DNA does not change any of his characters. Examples are like – acquiring knowledge, ideas, skills, weight loss etc.

Inherited traits: Inherited traits are those which are inherited from parents and pass from generation to generations. Change in DNA causes many changes. Examples are like – hair and eye color, muscle and bone structure, nose shape etc.

Question 3

why will there be two versions of each trait in a child

Answer 3

The rules for inheritance of such traits in human beings are related to
the fact that both the father and the mother contribute practically equal
amounts of genetic material to the child. This means that each trait can
be influenced by both paternal and maternal DNA. Thus, for each trait
there will be two versions in each child.

Question 4

define gene

Answer 4

genes are the basic unit of heredity and functional segments of DNA. They are responsible for the passing down of genetic traits from parent to offspring. They contain the code which is translated and transcribed by the cell to make protein which show the phenotype. They hold info the build maintain the cell

Question 5

what is a trait

Answer 5

It is a specific charcateristic of an indvidual that varies from one individual to another. EX: Colour of eyes- black, blue, attatches or free earlobe.

Question 6

define alleles

Answer 6

Alleles are alternate forms of genes. Every trait has atleast 2 alleles ( one from mother and one from father).
For e.g., The gene for eye color has several alleles. Two major alleles are: brown
and blue.

Question 7

define chromosome

Answer 7

Chromosome are condensed rods of thin thread like structures( chromatin material) which bears the genes and are encolsed in nucleus. They are formed at the time of cell devision and made up of dna and protein.

Question 8

differntiate between dominant and recessive alleles

Answer 8

dominant alleles are those alleles whcih are expressed phenotypically even when paired with another recessive allel. Whereas recessive alleles are expressed visibly only when paired with another recessive allele.

Question 9

differentiate between homozygous and heterozygous

Answer 9

Having two identical alleles for a particular gene
Having two different alleles for a particular gene

Question 10

what is a genotype

Answer 10

It refers to the genetic composition of an organism that decides the phsyical charcateristics of the organism
Tt, TT, tt

Question 11

what is a phenotype

Answer 11

It refers to the obersvable physical traits of an oranism
tall, shorrt

Question 12

who is mendel what is his contribution to geneitiscs

Answer 12

Gregor Johann Mendel is known as the Father of Genetics.Gregor Johann Mendel (1833 & 1884) started his experiments on plant breeding and hybridization.t Mendel
blended his knowledge of science and mathematics and was the first one
to keep count of individuals exhibiting a particular trait in each generation.
This helped him to arrive at the laws of inheritance

Question 13

what was the plant that was selected by mendel for his experiment

Answer 13

Plant selected by Mendel was Pisum sativum (garden pea). Mendel used a number of varieties of garden pea to
study the inheritance of seven pairs of contrasting characters.

Question 14

why did mendel chose the pea plant

Answer 14

Mendel choosed pea plants for experiments because :-
1.Pea is one year plant.It’s life cycle is very short. So in less time, study of many generations can be carried out.
2.Male and female reproductive organs are on one flower means flowers are bisexual. So it follows self pollination which makes it easier to get pure homozygous plants.
3.Bceuase of its floweral arrangement, it is easy to artifical cross pollination.
4.It grows in all seasons and is easily available
5. each plant produces many seeds
5.Pea plant has seven characteristics influenced by both dominant and recessive genes.examples:-Length of stem (tall and dwarf), Position of flowers (axial and terminal), color of fruit leaves (Green and yellow), Shape of fruit leaves (flat and constricted)„ Shape of seeds (Round and wrinkled) ,color of seed leaves (yellow and green),color of seed cover etc etc

Question 15

what is a punnett square

Answer 15

Diagram that can be used to predict the genotypes and phenotypes resulting from a genetic cross

It is a graphical
representation to calculate the probability of all
possible genotypes of offspring in a genetic cross.

Question 16

what is a monohypbrid cross

Answer 16

Monohybrid cross is a cross between two pea plants with one pair of contrasting characters. e.g., Cross
between a tall and a dwarf plant (short)
In case of monohybrid cross with pure line breeding varieties of plants, the phenotypic ratio obtained in F2
generation was 3:1.

Monohybrid cross is a type of genetic cross in only one pair of contrasting characteristics are considered

Question 17

what is dihybrid cross

Answer 17

Dihybrid cross is a cross between two plants having two pairs of contrasting characters.
e.g., Cross between green round seed with a yellow wrinkled seed.In case of dihybrid cross i.e., involving two pairs of contrasting characters, the phenotypic ratio obtained in F2
generation was 9:3:3:1.

Dihybrid cross is a genetic cross in which two pairs of contrasting traits are considered

Question 18

state law of dominance

Answer 18

Law of Dominance, which states that “When parents having pure
contrasting characters are crossed then only one character expresses itself in F1 generation. This character is the
dominant character and the character which cannot express itself is called recessive character”

Question 19

state law of independent assortment

Answer 19

Law of Independent Assortment states that the alleles of two different genes get inherited independently of one naother in a sexually reproducing organism

Mendel’s law of independent assortment states that the alleles of two (or more) different genes get sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene.

two factors of a character seperate and pair independently of the factors of another character during fertilisation. This results in recombination of genes

Question 20

How do traits or characters get expressed?

Answer 20

Genes control the expression of a trait or a character in an organism. Genes produces proteins. The proteins act as enzymes which can directly control a character or help in the formation of a hormone which can control the expression of a particular character or the proteins become a part of various structural components.

Question 21

how will a plant having Tt combination, trait be expressed ?

Answer 21

plants
have hormones that can trigger growth. Plant height can thus
depend on the amount of a particular plant hormone. The
amount of the plant hormone made will depend on the
efficiency of the process for making it. Consider now an enzyme
that is important for this process. If this enzyme works
efficiently, a lot of hormone will be made, and the plant will be
tall. If the gene for that enzyme has an alteration that makes
the enzyme less efficient, the amount of hormone will be less,
and the plant will be short.

Question 22

state law of segregation

Answer 22

During the development of gametes, each gene is segregated in such a way that a gemete receives only one allele for that gene

Law of segregation is the second law of inheritance. This law explains that the pair of alleles segregate from each other during meiosis cell division (gamete formation) so that only one allele will be present in each gamete. Two allels coding for the same trait separate during gamete formation.

2 factors of a character which are together in an organism seperate during gamete formation.
So, a gamete receives a single factor for that character. It is always pure for that character. its called the Law of Purity of Gametes