16.INHERITANCE

Question 1

What is inheritance?

Answer 1

The passing of genes from parents to their offspring or from generation to generation.

Question 2

Define genetics.

Answer 2

The study of inheritance.

Question 3

What is a gene?

Answer 3

A length of DNA that codes for a particular protein or polypeptide.

Question 4

What is an allele?

Answer 4

A particular variety of a gene.

Question 5

Define locus.

Answer 5

The position at which a particular gene is found on a particular chromosome.

Question 6

What is a diploid cell?

Answer 6

A cell whose nucleus contains two complete sets of chromosomes, written as 2n.

Question 7

What are somatic cells?

Answer 7

Diploid cells that contain 46 chromosomes (23 pairs) in humans.

Question 8

What is a haploid cell?

Answer 8

A cell whose nucleus contains one complete set of chromosomes, written as n.

Question 9

What are gametes?

Answer 9

Reproductive cells that are haploid (n), containing 23 chromosomes in humans.

Question 10

What happens when two haploid gametes fuse?

Answer 10

They form a diploid zygote.

Question 11

What is meiosis?

Answer 11

The type of nuclear division that produces haploid cells (gametes) from a diploid cell.

Question 12

What are homologous chromosomes?

Answer 12

Pairs of chromosomes that contain the same genes at the same positions but not necessarily the same alleles.

Question 13

What is the difference between meiosis I and meiosis II?

Answer 13

Meiosis I is a reduction division that halves the chromosome number; meiosis II is similar to mitotic division.

Question 14

What is crossing over?

Answer 14

The exchange of alleles between non-sister chromatids of homologous chromosomes during prophase I.

Question 15

What is independent assortment?

Answer 15

The production of different combinations of alleles in daughter cells due to the random alignment of bivalents during metaphase I.

Question 16

Define genotype.

Answer 16

The alleles of a particular gene possessed by an organism.

Question 17

What is a homozygous organism?

Answer 17

An organism with two identical alleles of a gene.

Question 18

What is a heterozygous organism?

Answer 18

An organism with two different alleles of a gene.

Question 19

What is phenotype?

Answer 19

The observable features of an organism, affected by genes and the environment.

Question 20

What are codominant alleles?

Answer 20

Alleles that both have an effect on the phenotype when present in a heterozygous organism.

Question 21

What is a test cross?

Answer 21

A genetic cross between an organism with a dominant phenotype and a homozygous recessive organism.

Question 22

What is monohybrid inheritance?

Answer 22

The inheritance of one gene.

Question 23

What is dihybrid inheritance?

Answer 23

The inheritance of two different genes.

Question 24

What is epistasis?

Answer 24

A condition where two different genes on different chromosomes affect the same feature.

Question 25

What is the phenotypic ratio in a typical dihybrid cross?

Answer 25

9:3:3:1.

Question 26

Fill in the blank: The F1 generation is the offspring resulting from a cross between a homozygous dominant genotype and a _______ recessive genotype.

Answer 26

homozygous

Question 27

True or False: All sex-linked genes are found on the Y chromosome.

Answer 27

False

Question 28

What is the role of the G allele in chicken feather color inheritance?

Answer 28

Codes for the pigment that produces colored feathers.

Question 29

What does the F allele do in chicken feather color inheritance?

Answer 29

Prevents the production of pigment even if G is present.

Question 30

What is the genotype for a white chicken that is homozygous dominant?

Answer 30

FFGG ## Footnote This genotype produces a white phenotype.

Question 31

What is the phenotype for the genotype ffGG?

Answer 31

coloured ## Footnote This genotype results in a coloured chicken.

Question 32

What does the allele 'G' produce in chickens?

Answer 32

colour ## Footnote The allele 'g' does not produce colour.

Question 33

What is autosomal linkage?

Answer 33

The presence of two genes on the same autosome that tend to be inherited together ## Footnote They do not assort independently during meiosis I.

Question 34

In Drosophila, what does the recessive allele 'e' represent?

Answer 34

black body with no stripes ## Footnote This phenotype is called ebony.

Question 35

What are the phenotypic ratios expected in a dihybrid cross between two heterozygous pea plants?

Answer 35

9:3:3:1 ## Footnote This ratio represents yellow seeds and round seed coats.

Question 36

What is the purpose of the chi-squared (X2) test?

Answer 36

To determine if the differences between observed and expected results are significant ## Footnote It helps to assess if differences are due to chance.

Question 37

What does a probability of 0.05 indicate in chi-squared testing?

Answer 37

There is a 5% chance that the difference is due to chance ## Footnote This is considered the critical probability level.

Question 38

What is the recessive allele in the TYR gene associated with?

Answer 38

Albinism ## Footnote This condition results in a lack of melanin.

Question 39

What genetic condition results from a mutation in the HBB gene?

Answer 39

sickle cell anaemia ## Footnote This is due to abnormal haemoglobin affecting red blood cells.

Question 40

What does the F8 gene code for?

Answer 40

coagulation factor VIII ## Footnote This protein is crucial for blood clotting.

Question 41

What is the dominant allele for height in pea plants?

Answer 41

Le ## Footnote It regulates the synthesis of gibberellins for stem elongation.

Question 42

What is a structural gene?

Answer 42

Codes for a structural protein required by the cell ## Footnote Example: Gene for lactase.

Question 43

What does a regulatory gene do?

Answer 43

Helps control the expression of other genes ## Footnote Example: Gene for repressor protein.

Question 44

What is an operon?

Answer 44

A functional unit of structural and regulatory genes working together ## Footnote Example: Operon for the production of B-galactosidase.

Question 45

How is albinism inherited?

Answer 45

As a recessive trait ## Footnote Individuals must be homozygous for the mutant allele.

Question 46

What happens to RBCs in sickle cell anaemia?

Answer 46

They become sickle-shaped and cannot transport O2 effectively ## Footnote This results from abnormal haemoglobin.

Question 47

What is the expected outcome for a cross between a homozygous stripped body fly and a homozygous ebony body fly?

Answer 47

All offspring have stripped bodies and normal antennae ## Footnote This is due to the dominance of the stripped body allele.

Question 48

What is the phenotype of a homozygous recessive chicken (ffgg)?

Answer 48

white ## Footnote This genotype results in a white phenotype.

Question 49

What is the relationship between genes, proteins, and phenotypes?

Answer 49

Genes code for proteins that determine phenotypes ## Footnote Example: TYR gene codes for tyrosinase affecting melanin production.

Question 50

What is the significance of the HTT gene?

Answer 50

It codes for the huntingtin protein involved in neuron development ## Footnote Mutations lead to Huntington's disease.

Question 51

What does the recessive allele le in pea plants cause?

Answer 51

Dwarfism ## Footnote It results in non-functional gibberellins.

Question 52

What is lactase used for by bacteria?

Answer 52

Hydrolyze lactose into glucose and galactose for energy.

Question 53

What type of gene codes for the production of B-galactosidase (lactase)?

Answer 53

Structural gene.

Question 54

What are regulatory genes?

Answer 54

Genes that control the expression of other genes.

Question 55

What is an operon?

Answer 55

A group of structural and regulatory genes that work together.

Question 56

What is the lac operon responsible for?

Answer 56

Production of B-galactosidase (lactase) and other related enzymes.

Question 57

What does Lac Z code for?

Answer 57

Galactosidase.

Question 58

What does Lac Y code for?

Answer 58

Permease, which allows lactose to enter the cell.

Question 59

What does Lac A code for?

Answer 59

Transacetylase, which transfers acetyl groups.

Question 60

What is a promoter?

Answer 60

A DNA region where proteins bind to initiate transcription.

Question 61

What happens to B-galactosidase production in the absence of lactose?

Answer 61

The lactose gene is switched off, and no B-galactosidase is produced.

Question 62

What is a repressor protein?

Answer 62

A protein that binds to the operator region to inhibit transcription.

Question 63

How does lactose affect the repressor protein?

Answer 63

Lactose binds to the repressor, distorting its shape and preventing it from binding to DNA.

Question 64

What occurs when lactose is present in the environment?

Answer 64

Transcription of the lactase gene is initiated, producing B-galactosidase.

Question 65

What is an inducible enzyme?

Answer 65

An enzyme synthesized only when its substrate is present.

Question 66

Give an example of an inducible enzyme.

Answer 66

B-galactosidase.

Question 67

What are repressible enzymes?

Answer 67

Enzymes produced continuously but can be inhibited by a signal.

Question 68

What is the role of transcription factors in eukaryotes?

Answer 68

Control gene expression by increasing or decreasing transcription rates.

Question 69

Do eukaryotes have operons?

Answer 69

No, they use transcription factors instead.

Question 70

How do gibberellins influence gene transcription?

Answer 70

By breaking down the DELLA repressor protein.

Question 71

What is the function of DELLA protein?

Answer 71

Inhibits transcription factors from binding to gene promoters.

Question 72

What does gibberellin promote in seed germination?

Answer 72

Synthesis of amylase.

Question 73

Fill in the blank: The operon responsible for lactase is called the _______.

Answer 73

lac operon.