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Question 1

Who conducted hybridisation experiments on garden peas?

Answer 1

Gregor Mendel

Mendel’s experiments were conducted between 1856 and 1863.

Question 2

What statistical methods did Mendel apply to biology during his experiments?

Answer 2

Statistical analysis and mathematical logic

Question 3

What is a true-breeding line?

Answer 3

A line that shows stable trait inheritance and expression for several generations through continuous self-pollination

Question 4

What were some of the contrasting traits Mendel selected in his pea plants?

Answer 4

• Smooth or wrinkled seeds
• Yellow or green seeds
• Inflated or constricted pods
• Tall or dwarf plants

Question 5

What is the Filial1 generation also known as?

Answer 5

F1 generation

Question 6

What did Mendel observe about the F1 progeny plants?

Answer 6

All were tall, resembling one parent; none were dwarf

Question 7

What was the observed ratio of tall to dwarf plants in the F2 generation?

Answer 7

3:1 (tall to dwarf)

Question 8

What term did Mendel use to describe the units of inheritance?

Answer 8

Factors

Question 9

What are genes defined as?

Answer 9

Units of inheritance that contain information to express a particular trait

Question 10

What are alleles?

Answer 10

Slightly different forms of the same gene that code for contrasting traits

Question 11

What symbols are used for dominant and recessive traits in Mendel’s example of height?

Answer 11

Capital letter for dominant (T) and small letter for recessive (t)

Question 12

What is the genotype of a plant that is heterozygous for height?

Answer 12

Tt

Question 13

What is the phenotype of a plant with the genotype Tt?

Answer 13

Tall

Question 14

What is a monohybrid cross?

Answer 14

A cross between two organisms that differ in one trait

Question 15

What does the Law of Dominance state?

Answer 15

• Characters are controlled by discrete units called factors
• Factors occur in pairs
• One member of a dissimilar pair of factors dominates the other

Question 16

What does the Law of Segregation explain?

Answer 16

Alleles segregate from each other during gamete formation, with each gamete receiving only one allele

Question 17

What is incomplete dominance?

Answer 17

A form of inheritance where the F1 phenotype is a blend of both parents’ traits

Question 18

What phenotype results from a cross between true-breeding red-flowered and white-flowered plants in snapdragons?

Answer 18

Pink flowers in the F1 generation

Question 19

What is the expected phenotype ratio in the F2 generation of snapdragons?

Answer 19

1 Red : 2 Pink : 1 White

Question 20

What is the significance of dominance in genetics?

Answer 20

It determines which traits are expressed in the phenotype over others

Question 21

What is a test cross?

Answer 21

A cross between an organism showing a dominant phenotype and a recessive parent to determine its genotype

Question 22

What ratio did Mendel find in the genotypes of a monohybrid cross?

Answer 22

1:2:1 (TT : Tt : tt)

Question 23

What does the Punnett Square illustrate?

Answer 23

The probability of all possible genotypes of offspring in a genetic cross

Question 24

What happens to the dwarf phenotype in successive generations according to Mendel’s findings?

Answer 24

Dwarf plants continue to produce dwarf offspring in F3 and F4 generations

Question 25

What is the expected phenotypic ratio in the F2 generation of a typical monohybrid cross?

Answer 25

3:1 (dominant to recessive)

Question 26

What was the conclusion regarding the genotype of dwarf plants?

Answer 26

The genotype of dwarfs was homozygous (tt)

Question 27

What is a diploid organism?

Answer 27

An organism with two copies of each gene, i.e., a pair of alleles.

Question 28

What is a heterozygote?

Answer 28

An organism with two different alleles for a particular gene.

Question 29

What can modifications in alleles lead to?

Answer 29

Changes in the information that a particular allele contains.

Question 30

What are the possible outcomes of a modified allele producing an enzyme?

Answer 30

* Normal/less efficient enzyme * Non-functional enzyme * No enzyme at all

Question 31

What happens when a modified allele produces a non-functional enzyme?

Answer 31

The phenotype/trait will depend on the functioning of the unmodified allele.

Question 32

What is the dominant allele?

Answer 32

The unmodified (functioning) allele that represents the original phenotype.

Question 33

What is the recessive allele?

Answer 33

The modified allele that may produce a non-functional enzyme or no enzyme.

Question 34

What is co-dominance?

Answer 34

A genetic scenario where the F1 generation resembles both parents.

Question 35

What gene controls the ABO blood grouping in humans?

Answer 35

Gene I.

Question 36

What are the three alleles of the ABO blood group gene?

Answer 36

* IA * IB * i

Question 37

How do alleles IA and IB interact with allele i?

Answer 37

IA and IB are completely dominant over i.

Question 38

What is the result when IA and IB are present together?

Answer 38

Both express their own types of sugars due to co-dominance.

Question 39

How many different combinations of the three I gene alleles are possible?

Answer 39

Six different combinations.

Question 40

Fill in the blank: The modified allele is generally the _______.

Answer 40

recessive allele.

Question 41

True or False: In co-dominance, the F1 generation resembles only one parent.

Answer 41

False.

Question 42

What determines the type of sugar present on red blood cells?

Answer 42

The alleles IA, IB, and i.

Question 43

What is the phenotype when only the unmodified allele is functional?

Answer 43

The phenotype will reflect the trait determined by the unmodified allele.