Biology exam paper questions - new
Use the data about the length of leaves in the two sites to explain why standard deviation is more useful
than range as a measure of variation within a population. ANS: Definition of range + SD / effect of
outliers on range + SD;
Ranges are similar in both are...
Biology exam paper questions - new
Use the data about the length of leaves in the two sites to explain why standard deviation is more useful
than range as a measure of variation within a population. ANS: Definition of range + SD / effect of
outliers on range + SD;
Ranges are similar in both areas;
Suggests that variation within populations is similar;
SD smaller in area of high light intensity;
Shows that area of high light intensity is a more uniform population;
describe the role of ribosomes in the production of a polypeptide. Do not include transcription in your
answer
( 3 marks) ANS: mRNa binds to ribosome
binding sites on the tRNa and the mRNA allows the anticodon to attach to the codon
the ribosome catalyses the formation of peptide bonds between amino acids, so that the amino acids
held by the tRNA molecule
In humans after the gametes join at fertilisation, every cell of the developing embryo undergoes mitotic
division before the embryo attaches to the uterus lining
> the first division takes
> the subsequent division each take 8 hours
after 3 days, the embryo has a total volime of 4.2 x 10⁻³ mm
What is the mean volume of each cell after 3 days? Express your answer in standard form.
( 2 marks ) ANS: How many divisions in total in 3 days = 7
- each division produces two daughter cells so
2 to the power of 7 = 128 cells produced in 3 days
128 cells have a volume of 4.2 x 10⁻³ mm
to find out the volume of one cell
we divide the 4.2 x 10⁻³ mm by 128
which equal to 3.28 x 10 ( to the minus 5 )
Some proteases are secreted as extracellular enzymes by bacteria ( saprobionts )
Suggest one advantage to a bacterium of secreting an extracellular protease in its natural environment
( 2 marks ) ANS: To digest protein;
, 2. (So) they can absorb amino acids for
growth/reproduction/protein synthesis/synthesis
of named cell component;
OR
(So) they can destroy a toxic substance/protein;
'' the antibiotics were given to the mice at a dose of 25mgkg per day
calculate how much antibiotic would be given to a 30 g mouse each day ANS: 25 mg per kg
the mouse is 30 mg = 0.03 kg
25 mg x 0.03 kg = 0.75 mg
The cell surface memebrane can be see with a TEM but not with an optical microscope
Explain why ANS: higher resolution and maginification than an optical microscope
Cell was stained before examination.
suggest an explanation why the cell surface membrane appeared as two dark lines ANS: stain binds to
the phosphate or glycerol heads of the phospholipid bilayer on the outside and inside of the membrane
Describe how substances move across cell surface membranes by diffisusion ( 3 marks ) ANS: substance
attaches to carrier or channel protein by complementary binding
changes its shape causing it to open on the inside of the cell so that the substance can move DOWN its
concentration gradient into the cell
when is meiosis ANS: when 2 x n ( diploid cells ) - with 46 chromosomes and 46 chromatids
divides into n ( haploid cells ) - with 23 chromosomes and 23 chromatids
importance of condensed chromosomes ANS: when cellls divide and move dna over, it is easy as it
makes it portable and organised
Suggest and explain advantages of sexual and a sexual reproduction of sporangia ANS: Asexual -
produces clones which maintains specific pheno and genotypes - can colonise new environments
Sexual - increses genetic diversity so a greater chance of survival
Effect of competitive inhibitor in rate of enzyme reaction ANS: If the substrate concentration is
increased, the effect of the inhibitor is reduced > likehood of enzyme substrate complexes forming is
increased as there is more active sites available
all the substrates will eventually occupy the active site but the greater the concentration of the
substrate, the longer this will take
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