2018 P2 Flashcards
Heat stress decreases the light-dependent reaction of photosynthesis. Explain why this leads to a decrease in the light-independent reaction. (2)
Less ATP
Less NADPH
A decrease in the activity of the enzyme rubisco would limit the rate of photosynthesis. Explain (2)
Less CO2 reacts with RuBP and less GP
Where precisely is rubisco found in a cell? (1)
Stroma
The scientists concluded that heat stress reduces the activity of rubisco in plant leaves by affecting rubisco activate. Evaluate (4)
Rubisco activity increases with temperature
Rubisco actives activity decreases at higher temperatures (over 30c)
Graphs suggest activase doesn’t affect activity of rubisco
However, no stats test
Tick a box next to the statement which describes which describes incorrectly the effect of the mutation in an exon of a gene (1)
- An inversion will result in a change in the number of DNA bases
How many tumour cells present after 4 weeks? (2)
1.9 x 10^25
Suggest one reason why it was important that the student left the apparatus for one hour after the yeast culture reached a constant temperature. (1)
so the oxygen is used
During her investigation the coloured liquid moved to the right. Explain why (2)
Anaerobic respiration produces CO2
which causes an increase in PRESSURE
Calculate the volume of gas produced in cm3 hour-1
4.9 x 10-4
Explain why a log scale is used to record he number of cells (1)
Large range of numbers
Many yeast cells die during the death phase. Why? (1)
Decrease in glucose
2000 yeast cells population after 10 hours. with given calculation (2)
297766
Describe how you would determine the mean percentage cover for beach grass on a sand dune (3)
Set up a numbered grid on the sand dune. Use a random number generator to select sections to be measured. Use a large sample size of quadrat sections. Divide total percentage by number of quadrats to find mean percentage cover.
The scientists concluded the results were due to succession. Explain why using Figure 5. (4)
Beach grass is PIONEER SPECIES
Pioneers change ABIOTIC FACTORS
so LESS HOSTILE for named species
Conifer and hardwood tress represent CLIMAX community
Use Figure 5 to explain Figure 6. (trees) (1)
Trees block sunlight
What can you conclude about the NPP in the sand dunes that are older than 1000 years?
NPP remains constant
GPP AND RESPIRATION constant
Suggest and explain one reason why they were given the same food (2)
Affects water potential of blood
Affects volume of urine produced
What can you conclude about the effectiveness of furosemide and CVT in the removal of excess fluid from the body (2)
Furosemide and CVT more effective than placebo
Significant difference as SDs do not overlap
Suggest how furosemide would cause a decrease in blood pressure. (1)
Lower VOLUME of blood
Explain how furosemide causes an increase in the volume of urine produced and where (3)
Water potential of filtrate decreased
Less water reabsorbed BY OSMOSIS from filtrate
Collecting duct is where this osmosis occurs
In genetic crosses, the observed phenotypic ratios obtained in the offspring are often not the same as the expected ratios. Suggest two reasons why (2)
SMALL sample size
Fertilisation of gametes is RANDOM
What would be the genotype of the offspring with dwarf plants and mottled leaves? (1)
T tall
M normal
ttmm
Explain results (mottled leaves dwarf plant one) (3)
Genes are LINKED
Produces FEW tall, mottled and dwarf, normal offspring
CROSSING OVER has occured
Ratio of offspring (mottled leaves dwarf plants one) (2)
9:3:3:1
9= tall normal
1= dwarf mottled
What is meant by a genome? (1)
ALL THE DNA in an organism
Explain why the antibody binds to the transcription factor (2)
Transcriptional factor has a specific TERTIARY STRUCTURE
so is COMPLEMENTARY to the antibody
Describe how farming cattle as a source of milk could have led to an increase in LP (4)
LP due to mutation
Milk provides GLUCOSE
Individuals with LP more likely to survive and reproduce
DIRECTIONAL selection occurs
Explain why the number of people showing LP would rapidly increase once selection for this condition had been established. (2)
DOMINANT allele ALWAYS expressed when present in offspring
Suggest and explain how this mutation causes LP (2)
Mutation in promoter for transcription factor
Lactase gene continues to be transcribed
