2018 P1 Flashcards
Give two pieces of evidence from Figure 1 that this cell was undergoing mitosis. (2)
The CHROMOSOMES are visible because they have CONDENSED
Chromosome is made up of two chromatids because DNA has REPLICATED
Tick one box that gives the name of the stage of mitosis shown in Figure 1. (1)
- Prophase
Suggest how this procedure moved the chromosomes apart. (2)
Water moves into the cells by OSMOSIS so cell gets BIGGER
Suggest one way the structure of the chromosome could differ along its length to result in the stain binding more in some areas. (1)
Differences in base sequences
What is a homologous pair of chromosomes? (1)
Two chromosomes that carry the same GENES
Give two ways in which the arrangement of prokaryotic DNA is different from the arrangement of human DNA in Figure 1. (2)
CIRCULAR not linear
Not associated with HISTONES
Describe the method the student would have used to obtain the results of Figure 3. Start after all potato cubes have been cut. (3)
Ensure all cut surfaces of the 8 cubes are FULLY SUBMERGED in sucrose solution
Control the TEMPERATURE
DRY cubes with filter paper to remove excess liquid BEFORE MEASURING
Is rate of osmosis per mm2 per min different between A and B during this time? (3)
A = 1.6 x 10^-5 B = 1.5 x 10^-5
Structure of amino acid (1)
R
H2N - C - COOH
H
What is meant by degenerate genetic code? (2)
MORE THAN ONE CODON codes for a single amino acid
eg. UCU UCA UCC UCG all code for Ser
What is the minimum number of bases in the gene coding for this polypeptide? (1)
465 x 3 = 1395
Use info in Table 1 to tick one box that shows a single base substitution mutation in DNA that would result in a change from Val to Ala at 203. (1)
MC
- CAA –> CGA
Use all the info and your knowledge of protein structure to suggest reasons for the differences between the effects of the two changes. (3)
Both NEGATIVELY CHARGED TO POSITIVELY CHARGED change in amino acid
Change at AA 300 doesn’t change shape of ACTIVE SITE
AA 279 may have been involved in a bond AND so shape of active site change
Complete Figure 7 to show the chromosomes content of cells that result from a normal meiotic division. (2)
- One big one small pair
2. One big one small single
Complete Table 3 to show expected number of plants… (2)
52 and 4
What does this result suggest about the difference between the observed and expected result and what can the scientists conclude (2)
There is a LESS than 0.05 probability that the difference BETWEEN observed and expected occurred by CHANCE
Calculated value is greater than critical value so the null hypothesis can be REJECTED
Use your knowledge of directional selection to explain the results shown in Table 3. (3)
The scientists selected breeding plants that produced 2n gametes
so these plants passed on their ALLELES to the next generation
so the FREQUENCY OF ALLELES for production of 2n gametes increased
The scientists concluded that this heat treatment damaged the phloem. Explain (2)
.Radioactively labelled carbon is CONVERTED INTO SUGAR during photosynthesis
.Mass flow in phloem throughout the plant is only in UNTREATED plants
The scientists also concluded that this heat treatment did not affect the xylem. Explain (2)
.The water content of the leaves was not different because the STANDARD DEVIATIONS OVERLAP
.Water is therefore still being transported in the xylem
What can you conclude about the movement of Fe3+ in barley plants? (4)
.Heat treatment has a greater effect on YOUNG leaves than old
.Heat treatment DAMAGES the phloem
.HIGHER RATIO OF FE3+ in old leaves than young
.But NO STATS TEST to show if the difference is significant
Describe gross structure of human gas exchange system and how we breathe in and out. (6)
1+2. Air moves into body via mouth –> trachea –> bronchi –> bronchioles –> alveoli
- BREATHING IN - diaphragm contracts and EXternal intercostal muscles contract
- causes volume increase and pressure decrease in thoracic cavity, which results in air moving in
- BREATHING OUT - diaphragm relaxes and INternal intercostal muscles contract
- causes volume decrease and pressure increase in the thoracic cavity, resulting in air moving out
Compare and contrast the structure and properties of triglycerides and phospholipids (5)
BOTH:
contain ester bonds
contain glycerol
insoluble in water
CONTRAST:
triglyceride has 3 fatty acids AND phospholipids have 2 fatty acids plus a phosphate group
triglycerides are hydrophobic AND phospholipids have a hydrophobic and hydrophilic region
Describe how lactose is formed and where in the cell it would be attached to a polypeptide to form a glycoprotein (4)
GLUCOSE + GALACTOSE join in a CONDENSATION reaction with a GLYCOSIDIC BOND.
It would be attached to a polypeptide in GOLGI
