B16: Inheritance

Question 1

What does the complex molecule DNA carry?

Answer 1

The genetic information of a cell

Question 2

List 2 descriptions about DNA.

Answer 2

1) DNA is very tightly coiled
2) DNA consists of a huge number of atoms

Question 3

What is a chromosome?

Answer 3

A thread-like structure made up of coiled and packed DNA in the nucleus of a cell

Question 4

How is genetic information in the DNA carried?

Answer 4

In the form of genes

Question 5

What is a gene?

Answer 5

A length of DNA that codes for a particular protein

Question 6

What are alleles?

Answer 6

Alternative versions of each gene. these produce variation in population, such as different eye and skin colours.

Question 7

What is a haploid?

Answer 7

A gamete that has a haploid nucleus contains a single set of unpaired chromosomes

Question 8

What is a diploid?

Answer 8

A body cells that has a diploid nucleus contains 2 sets of chromosomes

Question 9

What chromosomes do males have?

Answer 9

XY

Question 10

What chromosomes do females have?

Answer 10

XX

Question 11

How do people inherit sex chromones?

Answer 11

One from their father, and the other from their mother

Question 12

Which chromosome does the sperm cell have?

Answer 12

Has one X chromosome or one Y chromosome

Question 13

Which chromosome does the egg cell have?

Answer 13

Has one X chromosome

Question 14

Which gamete does the sex of a child depend on?

Answer 14

The sperm, whether it has an X or Y chromosome

Question 15

What is mitosis?

Answer 15

A type of nuclear division that gives rise to genetically identical cells. The cells produced by nuclear division are called daughter cells.

Question 16

Describe the process of mitosis (2)

Answer 16

1) In preparation for mitosis, each chromosome is replicated exactly so that there are 2 copies of each chromosome when the cell is about to divide. This is when they become visible under the microscope as X-shaped structures because the 2 copies are joined together near the middle
2) When the nucleus divides into 2, one copy of each chromosome goes into each new cell during cell division

Question 17

What is mitosis involved in? (3)

Answer 17

1) The repair of damaged tissues
2) Growth
3) Asexual reproduction

Question 18

What is produced at the end of mitosis?

Answer 18

2 identical daughter cells

Question 19

What is meiosis?

Answer 19

A type of nuclear division that gives rise to cells that are genetically different.

Question 20

Which nuclear division is involved with the production of gametes?

Answer 20

Meiosis

Question 21

List the steps of meiosis.

Answer 21

1) Each chromosome is exactly duplicated before meiosis begins. This is when they become visible under the microscope as X-shaped structures because the 2 copies are joined together near the middle.
2) Unlike mitosis, the number of chromosomes is halved, so it is called a reduction division. Each cell will have one chromosome of each pair
3) A diploid cell (with a nucleus containing 2 sets of chromosomes) becomes 4 haploid cells (each with a nucleus containing a single set of unpaired chromosomes)
4) The haploid cells formed are genetically different from each other and from the original diploid cells. This is because of crossing over, where the chromosomes swap parts with each other in the early stages of meiosis.

Question 22

What is inheritance?

Answer 22

The transmission of genetic information from generation to generation.

Question 23

How is genetic information is transmitted?

Answer 23

In the form of DNA

Question 24

What does homozygous mean?

Answer 24

Having two identical alleles of a particular gene.

Question 25

What does heterozygous mean?

Answer 25

Having two different alleles of a particular gene.

Question 26

What does phenotype mean?

Answer 26

The observable features of an organism

Question 27

What does genotype mean?

Answer 27

The genetic make-up of an organism in terms of its alleles (versions of genes)

Question 28

What is pure breeding?

Answer 28

If 2 identical homozygous individuals breed together, all of their offspring will inherit the same alleles, and show the same phenotype as their parents.

Question 29

What is a monohybrid cross?

Answer 29

The breeding of 2 individuals that differ in their alleles for a particular gene

Question 30

In what 2 ways can alleles be described?

Answer 30

Dominant or recessive

Question 31

What is a dominant allele?

Answer 31

An allele that is always expressed if it is present

Question 32

What is a recessive allele?

Answer 32

An allele that is only expressed if the dominant allele is not present

Question 33

What does a capital letter represent in punnet squares?

Answer 33

A dominant allele

Question 34

What does a lower case letter represent in punnet squares?

Answer 34

A recessive allele

Question 35

What is a phenotypic ratio?

Answer 35

The expected ratio of phenotypes in offspring produced by a cross.

Question 36

What is a pedigree diagram?

Answer 36

A type of family tree. It shows how a single characteristic is inherited by each family member

Question 37

What do squares represent in a pedigree diagram?

Answer 37

Males

Question 38

What do circles represent in a pedigree diagram?

Answer 38

Females

Question 39

What does a horizontal line represent in a pedigree diagram?

Answer 39

Connects parents

Question 40

What does a vertical line represent in a pedigree diagram?

Answer 40

Leads from parents to their offspring

Question 41

How are all offspring connected in a pedigree diagram?

Answer 41

Connected by a T-shape

Question 42

What are individuals who show inherited characteristic shown as on a pedigree diagram?

Answer 42

Coloured symbols or by symbols with diagonal lines

Question 43

What are individuals who do not show the characteristic shown as in pedigree diagrams?

Answer 43

White symbols

Question 44

What are carriers?

Answer 44

An individual who has a single copy of a recessive allele that is responsible for a genetic disorder or disease.