Chapter 17: Inheritance

Question 1

Define chromosomes.

Answer 1

A chromosome is a long length of DNA which carries genetic information in the form of genes.

Question 2

Define gene.

Answer 2

A section of DNA that codes for a protein.

Question 3

How do you control our characteristics?

Answer 3

By controlling the production of proteins.

There can be different versions of the same gene, which give different versions of a characteristics.

Question 4

Define allele.

Answer 4

An allele is an alternative version of a gene.

Question 5

What sex chromosomes do males have?

Answer 5

XY

Question 6

What sex chromosomes do females have?

Answer 6

XX

Question 7

What is the probability that the embryo could be a male or a female?

Answer 7

50%:50% chance

Question 8

Define diploid nucleus.

Answer 8

A nucleus that contains two sets of chromosomes.

Question 9

How many pairs of chromosomes are there in diploid cells?

Answer 9

23 pairs of chromosomes.

Question 10

Define haploid nucleus.

Answer 10

A nucleus that contains a single set of chromosomes.

Question 11

How many chromosomes do gametes have?

Answer 11

23 chromosomes.

Question 12

Describe the process of protein synthesis.

Answer 12

1) DNA is found in the cell nucleus. It can’t move out of the nucleus because it’s really big. The cell needs to get the information from the DNA into the cytoplasm.
2) This is done using a molecule called messenger RNA (mRNA).
3) Like DNA, mRNA is made up of bases. Each mRNA molecule is a copy of a gene. 4) mRNA is made in the nucleus and then moves to the cytoplasm.
4) Once in the cytoplasm, the mRNA passes through a ribosome
5) The ribosome assembles amino acids into protein molecules.
6) The sequence of bases in the mRNA determines the specific order of amino acids in the protein.

Question 13

Define mitosis.

Answer 13

Mitosis is a nuclear division that results in two genetically identical cells.

Question 14

What is mitosis used for?

Answer 14

Growth, cell replacement, repair of damaged tissues.
Used in asexual reproduction.

Question 15

Describe the process of mitosis.

Answer 15

The cell’s chromosomes are replicated exactly so you end up with twice the normal diploid number of chromosomes.

During mitosis, the chromosome copies separate and the nucleus divides.

Question 16

When is mitosis important?

Answer 16

In stem cells as they are unspecialised.

Question 17

Define meiosis.

Answer 17

Meiosis is a reduction division, which halves the chromosome number from diploid to haploid, resulting in four genetically different cells.

Question 18

Define inheritance.

Answer 18

The transmission of genetic information between generations.

Question 19

Define genotype.

Answer 19

The alleles an organism has (its genetic make up)

Question 20

Define phenotype.

Answer 20

The observable features of an organism

Question 21

Define homozygous.

Answer 21

Having two identical alleles for a particular gene

Question 22

Define heterozygous.

Answer 22

Having two different alleles for a particular gene

Question 23

Define dominant allele.

Answer 23

An allele that is always expressed if it is present.

Question 24

Define recessive allele.

Answer 24

An allele that is only expressed when the dominant version of the allele is not present in the organism’s genotype.

Question 25

What determines your phenotype?

Answer 25

your genotype

Question 26

Define sex-linked characteristic.

Answer 26

A feature that is coded for by a gene located on a sex chromosome, making it more common in one sex than in the other.

Question 27

What are sex-linked disorders?

Answer 27

Disorders caused by faulty alleles located on sex chromosomes are sex-linked genetic disorders.

Question 28

Define codominance.

Answer 28

When both of the alleles in a heterozygous organism are expressed and so both determine the organism’s phenotype.