Heredity and Evolution - Summary of Lesson

Que 

What is heredity


Ans 

The transmission of genetically based characteristics from parents to the offspring is called heredity


Que 

What are variations


Ans

Small differences among the individuals of the same species are called variations



Que 

Who discovered the basic principles of genetics


Ans

Gregar John Mendel end of 19th century discovered the basic principle of genetics



Que 

Which plant selected by Mendel for his experiments


Ans 

Mental selected the garden pea ( pisum Sativum) for his experiments


Que 

Why Mendel selected pea plant for his experiments


Ans 

Mendel selected pea plant for his experiments because of following reasons


1) there are many varieties where available in alternative forms of character


2) varieties where available and pure forms that produce the same type of generation after generation


3) pea plant are self pollinated and could be as well as cross pollinated artificially


Que 

What are the three mendel's law of inheritance


Ans 

Mendel summarised his result known as mendel's law of inheritance


1) Law of Dominance

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


The character which expresses is called dominant character and the one which has unexpressed is called recessive character


2) Law of Segregation

The two members of a pair of factors separate during the formation of gametes


3) Law of independent assortment

There are two pairs of characters the distribution of the alleles of one character into the gametes is independent of the distribution of the alleles of other character

Que
What are autosomes

Ans
Autosomes are the kind of chromosomes which determine general body features like complexion height colour except on humans have 22 pairs of a autosome 

               


Que 

What is sex chromosome

Ans 

These are kind of chromosomes that determine the sex of an organism every human has only one pair of sex chromosome


Que 

Describe the conditions when the child born is a son or a daughter

Ans 

The sex of the child depends upon the kind of sperm that fertilizes the egg

Daya contains only X chromosomes but the response contains both X and y chromosomes


a) if the egg(X) is fused by X bearing sperm the resulting combination is XX the female constitution and the child born is a daughter


b) if the egg(X) is fused by Y bearing sperm the resulting combination is XY the male constitution and the child born is a Son

Or 


The male cell carries one X and Y chromosome where as female cell carries two XX chromosomes 

The fusion of X chromosome bearing sperm of male cell with the X chromosome of female cell produces a female child

While the fusion of Y chromosome bearing sperm of male cell with X chromosome of female egg produces a male child


Therefore it is the contribution of father (sperm of male gamete) is determines the sex of newborn baby

Que
What are genes

Ans
It is a functional unit of heredity. That is present on the chromosome of cell nucleus characteristics which are transferred from parents to their offsprings generation to generation are controlled by genes during reproduction


Que
What do you mean by genotype

Ans
The set of genes present in the cells of an organisms. ie Genetic composition of an individual

Que
What is phenotype

Ans
The observable characteristics which are genetically controlled

Que
What do you mean by alleles

Ans
Every gene has two alternative forms for a character producing different effects these alternative forms are called alleles

Que
What is dominant Allele

Ans
The allele which expresses itself regardless of presence of another allele is for a given gene. It is represented by capital letter TT

Que
What is recessive allele

Ans
The allele whose expression is suppressed in the presence of a dominant allele for a given gene It is represented by small letter Tt

Que -- Define homogygous?

Ans
Condition in which one individual causes a pair of identical dreams controlling a given character that is occurrence of two identical It can be represented as TT

Que -- Define Heterogygous ?

Ans - condition in which an individual as a pair of contrasting jeans for any character that has existence of dominant and recessive alleles simultaneously .It can be represented as Tt


Que
What is monohybrid cross

Ans
Mendel cross to pure breeding varieties of pea plant by taking contrasting characters of one single character this is known as monohybrid cross

Que
What is dihybrid cross

Ans
Mendel cross to pure breeding varieties of pea plant by taking contrasting two different characters is called dihybrid cross

Que
What do you mean by F1 generation

Ans
When two homozygous pea plants with contrasting traits are crossed a heterozygous hybrid plant is obtained this is known as F1 generation

Que
What is F2 generation

Ans
When two hybrid plants of F1 generation are self crossed we obtain F2 generation


Que
What is the phenotypic monohybrid ratio in F2 generation

Ans. 

The phenotypic monohybrid ratio is 3:1

Que 

What is the phenotypic dihybrid ratio in F2 generation

Ans 

The dihybrid ratio in F2 generation. 9:3:3:1

    


Fri Nov 18, 2022

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