Inheritance

Question 1

What is the genome?

Answer 1

All of the genes present in an organism.

Question 2

What is a gamete?

Answer 2

Gametes are sex cells (sperm or eggs).

Question 3

What is a chromosome?

Answer 3

Tightly packaged DNA around histone proteins.

Question 4

How many chromosomes do human body cells have?

Answer 4

46 chromosomes (23 pairs)

Question 5

How many chromosomes do human gametes have?

Answer 5

23 chromosomes

Question 6

Where are chromosomes located?

Answer 6

In the nucleus of the cell

Question 7

What is a gene?

Answer 7

A section of DNA that codes for a protein.

Question 8

Describe the structure of DNA

Answer 8

• It is a polymer made of many nucleotide monomers
• It is made of 2 strands in the shape of a double helix

Question 9

Name the 4 bases in DNA

Answer 9

• Adenine (A)
• Thymine (T)
• Cytosine (C)
• Guanine (G)

Question 10

State 2 differences between DNA and RNA?

Answer 10

• DNA is double stranded whereas RNA is single stranded
• RNA contains Uracil (U) whereas DNA contains Thymine (T)

Question 11

How do the bases in DNA pair up?

Answer 11

Adenine pairs with Thymine (A with T)
Cytosine pairs with Guanine (C with G)

Question 12

Describe transcription

Answer 12

1) DNA unzipped
2) Complementary mRNA nucleotides bind and are joined together
3) mRNA detaches and leaves the nucleus

Question 13

What is a codon?

Answer 13

A group of 3 bases on the mRNA molecule that code for a single amino acid.

Question 14

What is an anticodon?

Answer 14

3 bases on a tRNA molecule that match the codon on the mRNA molecule

Question 15

Describe translation

Answer 15

1) mRNA travels to a ribosome
2) tRNA molecules with an anticodon that matches the codon on the mRNA molecule carry amino acids to the ribosome
3) The amino acids are joined together

Question 16

How does the sequence of bases affect the protein made in protein synthesis?

Answer 16

DNA is a triplet code where 3 bases code for one amino acid and the order of amino acids determine the protein produced.

Question 17

What is an allele?

Answer 17

Different versions of the same gene

Question 18

What is a dominant allele?

Answer 18

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

Question 19

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

Answer 19

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

Question 20

What is meant when an organism is homozygous?

Answer 20

When an organism has two copies of the same allele (two recessive or two dominant).

Question 21

What is meant when an organism is heterozygous?

Answer 21

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

Question 22

What is the genotype?

Answer 22

The genes present for a trait

Question 23

What is the phenotype?

Answer 23

The visible characteristic

Question 24

What is codominance?

Answer 24

When two alleles affect the phenotype

Question 25

What is monohybrid inheritance?

Answer 25

The inheritance of one allele

Question 26

Draw a Punnett square for a cross between a homozygous recessive blue eyed female (bb) with a heterozygous brown eyed male (Bb)

Answer 26

Question 27

Draw a Punnett square for a cross between a homozygous dominant red flower (RR) with a homozygous recessive white flower (rr)

Answer 27

Question 28

Draw a Punnett square for a cross between two heterozygous cystic fibrosis carriers (Ff)

Answer 28

Question 29

Draw a Punnett square to show how sex is determined

Answer 29

Question 30

What do family pedigrees show?

Answer 30

Question 31

Give 3 processes that require mitosis

Answer 31

- Growth - Repair - Asexual reproduction

Question 32

How many cells does mitosis produce?

Answer 32

One parent cell produces two daughter cells.

Question 33

How many cells does meiosis produce?

Answer 33

One parent cell produces 4 daughter cells.

Question 34

Give 2 differences between mitosis and meiosis

Answer 34

- Mitosis produces 2 genetically identical cells whereas meiosis produces 4 genetically different cells - Mitosis produces diploid cells whereas meiosis produces haploid cells

Question 35

What is random fertilisation?

Answer 35

- The random chance of a specific sperm combining with a specific egg - This increases variation as any female can mate with any male and any one of the millions of sperm could fertilise the egg

Question 36

What are the two types of variation?

Answer 36

Genetic variation and environmental variation

Question 37

State 2 traits in humans caused only by genetic variation

Answer 37

- Eye colour - Blood type

Question 38

State 2 traits in humans caused by a mix of environmental and genetic variation

Answer 38

- Height - Weight

Question 39

What is a mutation?

Answer 39

A random change in the genetic material of an organism.

Question 40

How do mutations alter the phenotype?

Answer 40

- Mutations alter the genetic material (DNA) - This can cause it to code for a different sequence of amino acids - A different sequence of amino acids means that the protein will be different

Question 41

Give 3 environmental factors that can increase the chance of mutations

Answer 41

- Exposure to UV radiation - Exposure to X-rays - Certain chemicals, particularly those found in cigarette smoke

Question 42

Describe the process of natural selection

Answer 42

- Populations are naturally varied due to random genetic mutations - Some of these mutations provide a selective advantage - These organisms survive and reproduce, passing on the successful genes

Question 43

Define evolution

Answer 43

Evolution is a change in the genetic makeup of a population over time due to natural selection.

Question 44

Describe how antibiotic resistance arises

Answer 44

- A random genetic mutation causes a bacterium to become resistant to the antibiotic - When the antibiotic is used, all the bacteria that do not have the mutation are killed - The population containing just the resistant bacteria then begins to grow

Question 45

What are the risks of antibiotic resistance?

Answer 45

Bacteria that cause infections that are resistant to antibiotics are hard to treat and can pose a serious threat to our health.