11 - Inheritance

Question 1

What is inheritance?

Answer 1

The transmission of genetic information from generation to generation.

Question 2

What is a chromosome?

Answer 2

A thread-like structure of DNA, carrying genetic information in the form of genes.

Question 3

What is a gene?

Answer 3

A length of DNA that codes for a protein.

Question 4

What is an allele?

Answer 4

A version of a gene

Question 5

What is a haploid nucleus?

Answer 5

A nucleus containing a single set of unpaired chromosomes (e.g. in gametes)

Question 6

What is a diploid nucleus?

Answer 6

A nucleus containing two sets of chromosomes (e.g. in body cells)

Question 7

How are chromosomes arranged in a diploid and a haploid cell respectively?

Answer 7

In a diploid cell, chromosomes are arranged in pairs. In a haploid cell there are 23 pairs.

Question 8

What sex chromosomes do people have?

Answer 8

Males have XY and females have XX.

Question 9

Who is responsible for determining the sex of the child?

Answer 9

A father, as he can pass on a Y chromosome.

Question 10

What is mitosis?

Answer 10

Nuclear division giving rise to genetically identical cells

Question 11

When does mitosis occur?

Answer 11

After the exact duplication of chromosomes.

Question 12

What is meiosis?

Answer 12

Reduction division in which the chromosome number is halved from diploid to haploid resulting in genetically different cells.

Question 13

What is meiosis involved in?

Answer 13

The production of gametes.

Question 14

How does mitosis occur in growth?

Answer 14

It produces new cells.

Question 15

How does mitosis occur in repairing?

Answer 15

It replaces damaged or dead cells

Question 16

How does mitosis occur in asexual reproduction?

Answer 16

Mitosis produces offspring that are genetically identical to the parent.

Question 17

What is a genotype?

Answer 17

The genetic make-up of an organism in terms of the alleles present.

Question 18

What is a phenotype?

Answer 18

The observable features of an organism

Question 19

What is homozygous?

Answer 19

Having two identical alleles of a particular gene

Question 20

What classifies as pure-breeding?

Answer 20

Two identical homozygous individuals that breed together are pure breeding, and a heterozygous individual will not be.

Question 21

What is heterozygous?

Answer 21

Having two different alleles of a particular gene

Question 22

What is a dominant allele?

Answer 22

An allele that is expressed if it is present

Question 23

What is a recessive allele?

Answer 23

An allele that is only expressed when there is no dominant allele of the gene present

Question 24

What is variation?

Answer 24

Differences between individuals of the same species.

Question 25

What is the difference between phenotypic variation and genetic variation?

Answer 25

Phenotypic variation is the difference in features between individuals of the same species, and genetic variation is when some of these differences are caused by differences in genes.

Question 26

What does continuous variation result in?

Answer 26

Continuous variation results in a range of phenotypes between two extremes (e.g. height in humans)

Question 27

What does discontinuous variation result in?

Answer 27

Discontinuous variation results in a limited number of phenotypes with no intermediates (e.g. tongue rolling)

Question 28

What is phenotypic variation caused by?

Answer 28

Genetic and environmental factors

Question 29

What is discontinuous variation caused by?

Answer 29

Genes alone (e.g. A, B, AB, and O blood groups in humans)

Question 30

What is a mutation?

Answer 30

A change in a gene or chromosome.

Question 31

What increases the rate of mutation?

Answer 31

Ionising radiation and some chemicals.

Question 32

What results in natural selection?

Answer 32

Individuals in a species show a range of variation, they produce more offspring than the environment can support. This leads to a competition for resources, which results in a ‘struggle for survival’. Higher chance of survival and more chances to reproduce for individuals more suited to the environment. Alleles resulting in these characteristics are passed to their offspring at a higher rate, which will lead to the next generation with a higher number of individuals with better adapted variations.

Question 33

What is evolution?

Answer 33

The change in adaptive features of a population over time as the result of natural selection.

Question 34

What is the process of adaptation?

Answer 34

The process resulting from natural selection by which populations become more suited to their environment over many generations.

Question 35

What is an example of evolution by natural selection?

Answer 35

The development of strains of antibiotic resistant bacteria.

Question 36

How does selective breeding occur?

Answer 36

Individuals with the desired characteristics are bred together, then their offspring with desired characteristics are bred together, and this is repeated for generations.

Question 37

What are the differences between natural and artificial selection?

Answer 37

Artificial selection only occurs when humans intervene, results in development of populations with features that are desired by humans and not features that will help them survive, and it takes less time as only individuals with desirable features are allowed to produce. Natural selection occurs naturally, results in development of populations with features that help them survive and adapt, and takes a longer time to occur.

Question 38

Why is selective breeding carried out?

Answer 38

It is carried out by artificial selection over many generations to improve crop plants and domesticated animals.