exam specific answers

Question 1

describe how two amino acids differ from each other? (1)

Answer 1

they have different R groups

Question 2

describe the role of tRNA in the process of translation? (3)

Answer 2

anticodon complementary to codon
specific amino acid
carried to ribosome
creates correct sequence of amino acids along polypeptide

Question 3

give two ways in which the structure of a tRNA and mRNA molecule are different? (2)

Answer 3

tRNA has clover leaf shape
tRNA has amino acid binding site
tRNA has anticodon available

Question 4

give three differences between mitosis and meiosis. (3)

Answer 4

mitosis/meiosis
one division/two divisions
genetically identical cells produced/genetically different cells produced
chromosomes don’t pair/chromosomes associate in pairs

Question 5

describe what happens to chromosomes in meiosis. (6)

Answer 5

chromosomes condense
chromosomes associate in homologous pairs
crossing over occurs
chromosomes joined to spindle by their centromere at equator of cell
homologous chromosomes move to opposite poles
in 2nd division pairs of chromatids separate

Question 6

describe how meiosis causes variation and explain the advantage of variation to species. (5)

Answer 6

crossing over
independent segregation of homologous chromosomes in meiosis 1 and 2
variation means some species better adapted
some survive, reproduce and pass on alleles
allows species to survive changes in environment