inheritance and reproduction

Question 1

Where are genetic materials stored in a cell?

Answer 1

The nucleus

Question 2

A chromosome is

Answer 2

Long lengths of DNA coiled up

Question 3

A gene is

Answer 3

A short section of DNA

Question 4

A DNA is in the shape of a

Answer 4

Double helix

Question 5

There can be different versions of the same gene, which give different versions of a characteristics, such as green or brown eyes. What are these called?

Answer 5

Alleles

Question 6

Complementary base pairs in DNA are:

Answer 6

A and T (adenine and thymine)
C and G (cytosine and guanine)

Question 7

Each gene in DNA codes for a protein, meaning that they decide our ——-

Answer 7

characteristics

Question 8

What is mitosis?

Answer 8

A cell reproduces itself by splitting to form two cells with identical sets of chromosomes

Question 9

Meiosis produces…

Answer 9

four haploid cells whose chromosomes are not identical

Question 10

Asexual reproduction uses which process?

Answer 10

Mitosis

Question 11

Gametes are produced in which process?

Answer 11

Meiosis

Question 12

Protein synthesis has two stages

Answer 12

Transcription and translation

Question 13

Translation is:
(In simple terms)

Answer 13

Using the mRNA strand to make a protein

Question 14

Transcription is:
(In simple terms)

Answer 14

A single gene is taken and copied into mRNA

Question 15

mRNA uses a different base - what is the base that has been removed and what has it been replaced with?

Answer 15

REMOVED: thymine - T
REPLACED WITH: uracil - U

Question 16

mRNA stands for -

Answer 16

messanger RNA

Question 17

tRNA stands for -

Answer 17

transfer RNA

Question 18

Genetic variation definition

Answer 18

Is the difference in DNA sequences of individuals within the same species caused by mutations

Question 19

Meaning of evolution

Answer 19

A change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species

Question 20

Why are bases important?

Answer 20

They code for amino acids which form the protein

Question 21

mRNA makes a copy of DNA to take to the…

Answer 21

Ribosome

Question 22

The process of transcription (in steps)

Answer 22

• RNA polymerase binds to the DNA just before the gene begins
• the two strands of DNA separate after the RNA polymerase so the bases are exposed
• the RNA polymerase will read the strand of DNA’s bases and make a mRNA strand using the complementary bases (G to C, A to U)
• the DNA then closes after the RNA polymerase has moved onto the next base, and opens at the front so it can read the next one so less DNA is exposed
• RNA polymerase detaches and DNA closes
• mRNA can now leave the nucleus and go to the ribosome

Question 23

What is used to make mRNA?

Answer 23

Part of DNA - template strand
The reader - RNA polymerase

Question 24

The process of translation (in steps):

Answer 24

• tRNA have an amino acid at the top and an anti codon at the bottom and will be attracted to the corresponding triplet
• the ribosome then joins the amino acids at the top of the two tRNAs that have been coded for
• it moves along the mRNA and does it to the next codon
• the first tRNA detaches, but leaves the amino acid, so the tRNA is able to join the 2nd and 3rd tRNAs
• this forms a chain of amino acids after being repeated again and again
• the chain then folds up and becomes a protein

Question 25

The codons (three bases) code for:

Answer 25

Amino acids/proteins

Question 26

Where does transcription take place?

Answer 26

The nucleus

Question 27

Where does translation take place?

Answer 27

The ribosome

Question 28

How is mRNA different to DNA?

Answer 28

It is single stranded and shorter

Question 29

A chain of amino acids is called a

Answer 29

Polypeptide

Question 30

What is a gamete?

Answer 30

An organisms reproductive cell that has half the number of chromosomes

Question 31

Heterozygous

Answer 31

When one of the inherited alleles is dominant and the other is recessive

Question 32

Dominant allele

Answer 32

Only one out of the two alleles is needed for it to be expressed and for the corresponding phenotype to be observed

Question 33

Two copies are needed for it to be expressed in the phenotype

Answer 33

Recessive allele

Question 34

Homozygous

Answer 34

When both inherited alleles are the same (eg two dominant or recessive alleles)

Question 35

Codominance

Answer 35

When neither allele is dominant so both contribute to the phenotype

Question 36

What is variation?

Answer 36

It is the difference in DNA sequences of individuals within the same species

Question 37

What influences variation?

Answer 37

• GENETIC FACTORS - dependent on alleles
  eg eye colour or blood type
• ENVIRONMENTAL FACTORS - it is caused by differences in lifestyle, diet and climate which could lead to organisms adapting
• GENETICS AND ENVIRONMENTAL FACTORS eg height - some is genetic and some is food

Question 38

Variation occurs in meiosis because

Answer 38

Random fertilisation increases genetic variation as the fusing of sperm and egg are random
Gametes have random chromosomes so this increases variation
—> siblings do not have the same genes despite having the same parents

Question 39

what are the names of the bases in DNA

Answer 39

adenine - thiamine
cytosine - guanine
—> thiamine becomes uracil