Inheritance

Question 1

What did Kolventer discover in the 18th centuary?

Answer 1

Nicotiana (tobacco) reciprocal hybrids equivalent. Not all “information” came from one parent

Question 2

What did Knight discover in 1799?

Answer 2

Pea stem & flower purple pigment
			Reciprocal hybrids equivalent
			F1 all pigmented
			F2 reappearance of non-pigmented form
 He made no attempt to explain these important results.

Question 3

What did darwin discover ?

Answer 3

Scored Antirrhinum inheritance in individuals (instructed by his cousin Francis Galton). This data was later interpreted by Bateson to show Mendelian inheritance

Question 4

When was Gregor Mendel paper presented and published?

Answer 4

Presented in 1865

Published in 1866

Question 5

In 1875 who observed process of fertilisation

Answer 5

Hertwig

Question 6

When did Hertwig and Strasburger suggested the cell nucleus was the location of the heredity function

Answer 6

1885

Question 7

Define gene

Answer 7

unit of inheritance often responsible for one trait

Question 8

Define allele

Answer 8

alternative states / mutations of a particular gene

Question 9

Define homozygous and heterozygous

Answer 9

HOMO- identical alleles at the gene loci, producing identical gametes

Hetro- different alleles so different gametes

Question 10

Define dominant and recessive

Answer 10

Dominant- allele trait always expressed

Recessive- allele trait only expressed if homozygous

Question 11

Define phenotype

Answer 11

the expression of a character in an organism

Question 12

Define genotype

Answer 12

the allelic hereditary constitution

Question 13

P1 means?

Answer 13

parental generation

Question 14

F1 means?

Answer 14

First filial generation, progeny from parents

Question 15

F2 means?

Answer 15

Second filial generation, progeny resulting from F1 cross

Question 16

How do we denote genes?

Answer 16

A (upper-case) = Dominant allele. a (lowercase) = recessive allele
In Drosophila: letter denotes the mutant allele “+” = wildtype allele

Question 17

What are Mendel’s 4 postulates and laws of inheritance?

Answer 17

1) principles of paired factrors
2) principle of dominance
3) Law of Segregation/Law of purity of Gamtes (1st LAW)
4) Law of independent assortment (2nd LAW)

Question 18

What are the 5 advantages of using peas for genetics?

Answer 18

1) A number of discrete traits that can be studied
2) Self fertilizing
3) Numerous viable and fertile progeny
4) Short generation time
5) Can carry out crosses between different individuals by emasculation of anthers before pollen ripe and transfer of pollen from alternate parent

Question 19

Do a monohybrid cross for One tall and one short tree

Answer 19

TTxtt = all Tt

Question 20

In the F2 cross of TT and tt plants. What is the ratio of the resulting plants?

Answer 20

Tt xTt =

0. 25 TT
1. 25 tt
2. 5 Tt

Question 21

What is the ratio usually seen in F2 generation from 2 homozygous ‘parents’

Answer 21

3:1

Question 22

What is a dihybrid cross?

Answer 22

2 genes on different chromosomes each with 2 alleles

Question 23

What is independent assortment?

Answer 23

When alleles are unlinked in dihybrid crosses

Question 24

Do this dihybrid cross.
T is dominant to t
G is dominant to g

Answer 24

TG Tg tG tg x TG Tg tG tg

9:3:3:1

Tall green	(T-G-) = TTGG, TTGg, TtGG, TtGg
Tall yellow 	(T-gg) = TTgg, Ttgg
Short green 	(ttG-) = ttGG, ttGg
Short yellow 	(ttgg) = ttgg

Question 25

What is the mathematical rules of complete dominance with gene loci on different chromosomes F2?

Answer 25

No of heterozygous gene pairs- n
No of diff. types of gametes form - 2^n
No of diff. genotypes produced- 3^n
No of diff. phenotypes produced- 2^n