Inheritance -1

Question 1

State what is meant by the term gamete. (2)

Answer 1

*organism’s reproductive cell
*half number of chromosomes

Question 2

State what is meant by the term genome. (1)

Answer 2

*entire DNA of organism

Question 3

State what is meant by gene. (2)

Answer 3

*short section of DNA
*that codes for a specific protein

Question 4

State what is meant by Allele. (1)

Answer 4

*different form of gene

Question 5

State what is meant by the term codominance. (2)

Answer 5

*when neither of the allele is dominant over the other
*so both contribute to the phenotype

Question 6

What is meant by the term recombinant? (1)

Answer 6

• Contains new DNA

Question 7

*State two differences between mRNA and DNA. (2)

Answer 7

*mRNA contains uracil instead of thymine which DNA contains
*mRNA has a single strand, DNA is a double strand
*mRNA has ribose sugar while DNA contains de-ox ribose

Question 8

Describe how protein is made in a cell. (5)

Answer 8

*transcription occurs
*mRNA leaves nucleus
*enters ribosomes
*tRNA brings attached amino acids
*complimentary base pairings are formed
*translation/polypeptide chains are formed

Question 9

Describe the process of transcription within the nucleus. (5)

Answer 9

*Hydrogen bonds between base pairs break
*DNA unwinds
*exposes the template strand
*mRNA nucleotides match their complimentary base on the strand
*mRNA nucleotides are joined together
*forming mRNA molecule
*mRNA molecule leaves nucleus

Question 10

Describe the process of translation. (5)

Answer 10

*mRNA attaches onto ribosome
*tRNA molecules transport specific amino acids to ribosome
*each mRNA codon codes for a specific a.a
*anti-codons and codons form complimentary base pairings
*peptide chains are formed

Question 11

If a drug binds to mRNA, how will this affect protein synthesis? (5)

Answer 11

*drug will prevent mRNA from bonding with ribosome
*tRNA wont be able to read first codon
*no anti codons cannot match to codons
*no complimentary base pairings
*no amino acids deposited
*no peptide bonds form
*no protein is made

Question 12

Suggest what is meant by the term polygenic characteristics. (1)

Answer 12

*characteristics controlled by more than one gene

Question 13

Explain why the human population is almost 50:50 male or female. (3)

Answer 13

*Males produce X and Y - carrying sperm
*females only produce X - carrying eggs
*50% chance for either X or Y to fertilise egg

Question 14

State what is meant by diploid cell. (1)

Answer 14

*two sets of chromosomes, 46 chromosomes

Question 15

Give four ways mitosis is important for multicellular organisms. (4)

Answer 15

*growth
*asexual reproduction
*repair
*cloning

Question 16

Describe the process of Mitosis. (4)

Answer 16

*DNA replication occurs
*chromosomes are replicated
*chromosomes line up at center of cell
*spindle fibres pull chromatids to either side of cell
*cytoplasm divide into two daughter cells

Question 17

Describe the process of meiosis. (4)

Answer 17

*DNA replication occurs
*chromosomes are replicated
*chromosomes line up at center of cell
*spindle fibres pull chromatids to either side of cell
*cytoplasm divide into two daughter cells
*cell divides again
*4 daughter cells with 23 chromosomes each formed

Question 18

Explain why meiosis forms genetically different gametes. (2)

Answer 18

*chromosomes are shuffled during process
*random chromosomes ending up in each of the four cells

Question 19

State why there is genetic variation in offspring in fertilisation. (1)

Answer 19

*each zygote formed will have unique combinations of alleles

Question 20

Suggest what is meant by variation. (2)

Answer 20

*difference in DNA sequence within same species
*within same species

Question 21

State how the change in the DNA can affect the phenotype. (1)

Answer 21

*by altering the sequence of amino acids in a protein

Question 22

Give the three main types of mutations. (3)

Answer 22

*substitution
*deletion
*insertion

Question 23

Explain how substitution affects the protein that is coded for. (3)

Answer 23

*different nucleotide is added
*changes triplet code
*may change amino acid

Question 24

State one type of chemical mutagen that increases mutations. (1)

Answer 24

*tar in tobacco

Question 25

Explain how a random mutation in a bacterial population can lead to the evolution of antibiotic resistance. (5)

Answer 25

*random mutation *allele that codes for antibiotic resistance *when bacteria pop. exposed to antibiotic, those without resistance die *those with resistance survive *able to reproduce *pass on advantageous allele *over generations, frequency of resistance increases

Question 26

Explain why most genetic mutations have no effect on phenotype. (3)

Answer 26

*different sequences code for same a.a *no change in protein/enzyme *no change to active site *mutation may be recessive