Principles of Inheritance and Variations

Question 1

what is Filial progeny?

Answer 1

1st generation progeny of cross breeding two true-breeds.
its usually refered as F1.

Question 2

what is Gene?

Answer 2

A unit of inheritance.
they contain the information that is required to express a particular trait in an organism.

Question 3

What is an allele?

Answer 3

Allele are the variance of gene for a particular unit of inheritance. They are slightly different forms of the same gene.

Question 4

what is a genotype?

Answer 4

Genotype is the genetic constitution of a trait.

Question 5

what is a phenotype?

Answer 5

A set of observable charecters of an individual resulting from the interaction of its genotype with the environment.

Question 6

What is a difference between dominance and recessive?

Answer 6

A gene comes in a pair of alleles and it could be homozygous or hetrozygous. in the case of hetrozygous the one allele(the dominant) overrules the other (recessive).
for the recessive gene to show up on the phenotype, the pair of alleles should be homozygous of the recessive gene.

Question 7

what is monohybrid and dihybrid?

Answer 7

monohybrid is an organism with only one gene controlling charecter is hetrozygous.
dihybrid is an organism with only two gene controlling charecter is hetrozygous.

Question 8

what is an monohybrid cross?

Answer 8

when you cross two true beed organism that has one different traits.

Question 9

what is the binomial equation of writing the punnet squares ratio of f2 generation?

Answer 9

(ax+by)2

Question 10

whats a test cross?

Answer 10

test cross is an a test conducted to find if genotype of a plant is homozygous or hetrozygous by cross breeding the genotype unknown plant with know recessive phenotype plant and using the result of the progeny to interpret the genotype.

Question 11

what are the 2 laws of inheritance?

Answer 11

Law of Dominance & Law of Segregation.

Question 12

what is the law of dominance?

Answer 12

• The charectors are controlled by discrete units of factors
• The factors occur in pair
• In dissimilar pair of factors one member of the pair dominate the other.

Question 13

What is the law of segregation?

Answer 13

• Alleles do not blend
• The alleles are segregated in the process of meiosis before transfering to gamete.
• only one allele is tranfered to the gamete.
  in homozygous its all the same but in an hetrozygous plant 2 kinds of gametes are produced each having one allele with an equal propotion.

Question 14

What is in incomplete dominance?

Answer 14

when the dominant allele doesnt completely overrule the recessive allele.
The f1 generation of monohybrid cross results in progenies that are dissimalr to either of its parents.
when the genotype is hetrozygous the phenotype is different from both parents.

Question 15

Explain how an allele become dominant?

Answer 15

dominant allele are the normal allele and the recessive allele is the modified version of the normal allele.

normal alleles usually means there is product that has a certain function and the modification of that allele can cause the allele (1)to have a product that does same/less efficiant function (2) to have the product but no funtion (3) or no product at all.

the modified (1) allele wont cause any change to the phenotype but the 2 & 3 can affect the phenotype.

Question 16

What is Co-dominance and give an example?

Answer 16

Co-dominance occur when the traits of both the alleles show in the phenotype.
eg: Blood type ABO
gene - IA, IB, I. there are 3 alleles for blood type gene
If IAIB is the allele the traits of both AB is shown in blood type.

Question 17

Law of Independent assortment?

Answer 17

When 2 pairs of allele are combined in a hybrid, segregation of charector in one pair is independent of the other pair.

Question 18

Chromosomal Theory of Inheritance?

Answer 18

• Segregate at the time of gamete
  formation such that only one of each
  pair is transmitted to a gamete.
• Independent pairs segregate
  independently of each other.

Question 19

who were the other scientist that discovered mendels principles of inhertitance

Answer 19

Hugo de vries, Carl corren, and Erich Von Tschermak. All 3 of them discovered mendels principle independently around 1900.

Question 20

Who came up with the chromosomal theory of inheritance?

Answer 20

Walter sutton & Theodore Boveri

Question 21

What organism did Thomas Hunt morgan experimented with?

Answer 21

Drosophila melanogaster (common fruit fly)

Question 22

Why was fruit fly used in Morgans experiment?

Answer 22

• They are easy to grow in the lab
• The complete life cycle in 2 weeks
• Single mating produces large number of progeny
• Clear distinction btw Males & Females
• they form many types of Heriditary variations.

Question 23

What is Linkage?

Answer 23

The physical association of genes on a chromosome.

Question 24

What is recombination?

Answer 24

The process by which peices if DNA are broken and recombined to produce new combination of alleles.

Question 25

whats the relation btw Linkage and recombination?

Answer 25

the stronger the Linkage the lower the possibility of recombination.

Question 26

Who is Alfred Stuartevent and what did he do?

Answer 26

Alfred was a student of Morgan who worked with him on the experiment of drosophila melanogaster.
He used the frequancy of recombination occured between gene pairs on the same chromosome and used it as a measure of the distance between the genes in the chromosome. then mapped the genes position on the chromosome.
This technique was the basis for gene mapping.

Question 27

What is Polygenic Inheritance?

Answer 27

Polygenic traits are traits that are controlled by 3 or more genes and they are influneced by the environment. such traits are usually seen as a gradient trait.
eg:- height
the alleles in polygenic traits are additive.

Question 28

What is Pleiotropy?

Answer 28

A gene that has multiple phenotypic expression.
The reason for that is it usually affects a gene on the metabolic pathway.
eg :- Phenyl ketonuria

Question 29

What are the different types of sex determination?

Answer 29

XY type - humans
XO type - certain insects
ZW type - birds (Female heterogamety
Haplodiploid (number of chromosome) - Honey bee

Question 30

Fun fact about bees?

Answer 30

Bees cannot have father or son but can have grandfather and grandson.

Question 31

What is Mutation?

Answer 31

its a phenomenon that results in the alteration of DNA sequance which results in the change of genotype & phenotype of an organism.
mutation leads to variation in DNA.

Question 32

types of mutation?

Answer 32

deletion and Insertion/duplication of a Segment of DNA

Question 33

What is point mutation?

Answer 33

Mutation caused due to a change in a single base pair of DNA
eg:- Sickle-cell anemia

Question 34

What is a Mutagen?

Answer 34

Chemical & physical factors that induce mutation.
eg:- UV radiation

Question 35

What is pedigree Analysis? what is it used for?

Answer 35

Study of inheritance of gene over generations of a family.
it can be used as a tool to trace the inheritance of a specific trait, abnormality or disease.

Question 36

What are the 2 types of genetic disorder?

Answer 36

Mendelian disorder & chromosomal dissorder?

Question 37

What is mendelian dissorder?

Answer 37

Alteration or mutation in a single gene.
eg:- Haemophilia, cystic fibrosis, sickle cell anemia

Question 38

Are mutated/altered gene dominant or recessive?

Answer 38

it can be both dominant and recessive.

Question 39

What is chromosomal disorder?

Answer 39

Such disorders are caused due to absence/excess/abnormal arrangement of one or more chromosomes.

Question 40

Mention the advantages of selecting pea plant for experiment by Mendel.

Answer 40

• Easy to breed and cross
• Easily distinguishable phenotypes
• quick growth

Question 41

A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced?

Answer 41

16 gametes.