Topic 17

Question 1

What is inheritance?

Answer 1

Transmitting genetic information from one generation to the next

Question 2

What is a chromosome?

Answer 2

Long lengths of DNA + carries information in the form of genes

Question 3

What is a gene?

Answer 3

A section of DNA that codes for a specifc protein

Question 4

What is an allele?

Answer 4

Different versions of the same gene

Question 5

How is sex determined by genes?

Answer 5

“One of the 23 pairs of chromosomes determines sex
The pair can either be XX for a female or XY for a male”

Question 6

Describe how genes determine the order of amino acids in a protein

Answer 6

The sequence of bases in a gene relates directly to the amino acids added during protein synthesis

Question 7

How does DNA control cell function?

Answer 7

DNA codes for proteins which can be enzymes, antibodies and receptors (for example)

Question 8

Explain protein synthesis

Answer 8

“A copy of the gene is made using mRNA and taken into the cytoplasm to a ribosome
The ribosome assembles amino acids into proteins based on the sequence of bases in the mRNA molecule”

Question 9

Compare the genes found in all the body cells

Answer 9

“All body cells contain the same genes
However not all cells express all, only needed ones for their function

Question 10

What is a haploid nucleus

Answer 10

A nucleus with one set of unpaired chromosomes

Question 11

What is a diploid nucleus

Answer 11

A nucleus with two sets of chromosomes where there is a pair of each type of chromosome

Question 12

How many pairs of chromosomes does a human diploid cell have

Answer 12

23 pairs

Question 13

What is mitosis?

Answer 13

A type of nuclear division that produces two genetically identical daughter cells

Question 14

State 4 uses of mitosis

Answer 14

Cell growth
Repair of cells
Replacements of cells
Asexual reproduction

Question 15

When does the duplication of chromosomes happen in relation to mitosis?

Answer 15

“The duplication of the chromosomes happens before mitosis
“

Question 16

What are stem cells?

Answer 16

Cells that can differentiate into many different types of cells

Question 17

What is meiosis?

Answer 17

A type of reduction division which halves the chromosome number, producing four genetically different daughter cells

Question 18

What type of cell does meiosis produce?

Answer 18

Sex cells (gametes)

Question 19

How does meiosis produce genetically different daughter cells?

Answer 19

Meiosis combines maternal and paternal chromosomes in different ways

Question 20

What is the genotype?

Answer 20

The alleles present

Question 21

What is the phenotype?

Answer 21

The visible characteristic

Question 22

What is meant when an organism is homozygous?

Answer 22

Having 2 identical alleles for a particular gene

Question 23

What is meant when an organism is heterozygous?

Answer 23

When an organism has two different versions of the same gene (one dominant and one recessive)

Question 24

What is the term used to describe the type of breeding carried out when two homozygous individuals breed?

Answer 24

Pure-breeding

Question 25

What is a dominant allele?

Answer 25

A version of a gene where only one copy is needed for it to be expressed

Question 26

What is a recessive allele?

Answer 26

A version of a gene where two copies are needed for it to be expressed

Question 27

What do family pedigrees show?

Answer 27

The inheritance of an allele over generations

Question 28

What is a test cross?

Answer 28

"A method used to identify an unknown genotype It is done by breeding the unknown organism with a homozygous recessive organism"

Question 29

What is codominance?

Answer 29

When two alleles affect the phenotype

Question 30

What is a sex-linked characteristic?

Answer 30

"A characteristic where the gene responsible for its located on a sex chromosome This makes it more common in one sex than another"

Question 31

Give one example of a sex-linked characteristic?

Answer 31

Colour blindness