Thursday 25 May 2017 Flashcards
Name the bond between the phosphate and sugar?
Phosphodiester bond
DNA helicase
- (unwinding DNA and) breaking hydrogen bonds
DNA polymerase
- joins (adjacent) nucleotides
- forms phosphodiester bond / sugar- phosphate backbone;
Contrast the structures of ATP and a nucleotide found in DNA to give two differences.
- ATP has ribose and DNA nucleotide has deoxyribose;
- ATP has 3 phosphate (groups) and DNA nucleotide has 1 phosphate (group);
- ATP- base always adenine and in DNA nucleotide base can be different / varies;
Explain the purpose of: boiling the agar
So no contamination/ other bacteria;
Transferring the same volume of liquid culture onto each agar plate.
So same number of bacteria transferred to allow comparison;
The student concluded that the minimum concentration of propan-2-ol needed to stop the growth of Lactobacillus was 15 units. This conclusion is incorrect.
Describe how you could obtain a more accurate estimate of the minimum concentration of propan-2-ol needed to stop the growth of this species of bacterium.
- Take several values between 10 and 15 units
- Repeat each
Process by which fatty acids and glycerol enter the intestinal epithelial cell.
Diffusion
Explain the advantages of lipid droplet and micelle formation. 3 marks
- Droplets increase surface areas (for lipase / enzyme action);
- (So) faster hydrolysis / digestion (of triglycerides / lipids);
- Micelles carry fatty acids and glycerol / monoglycerides to / through membrane / to (intestinal epithelial) cell;
How is the Golgi involved in the absorption of lipids?
- Modifies triglycerides
- Combines trigylcerides to proteins
- Forms vesicles
Explain the role of the heart in the formation of tissue fluid.
- Contraction of ventricle(s) produces high blood / hydrostatic pressure;
- (This) forces water (and some dissolved substances) out (of blood capillaries);
Lymphoedema is a swelling in the legs which may be caused by a blockage in the lymphatic system.
Suggest how a blockage in the lymphatic system could cause lymphoedema.
Excess tissue fluid cannot be (re) absorbed/builds up;
Which test could the scientists have used to identify that there are amino acids in white wine?
Biuret
Draw a box around the part of the molecule that would be the same in all amino acids.
H2N – C – COOH; H
Name the chemical element found in all amino acids that is not found in triglycerides.
Nitrogen
Explain how the chromosome number is halved during meiosis.
- Homologous chromosomes (pair);
2. One of each (pair) goes to each (daughter) cell / to opposite poles;
What is the haploid number of chromosomes for this species of moss?
6
Describe the process of crossing over and explain how it increases genetic diversity.
- Homologous pairs of chromosomes associate / form a bivalent;
- Chiasma(ta) form;
- (Equal) lengths of (non-sister) chromatids / alleles are exchanged;
- Producing new combinations of alleles;
Describe how you would use cell fractionation techniques to obtain a sample of chloroplasts from leaf tissue. Do not include in your answer information about any solutions.
- Macerate / homogenise / blend / break tissues / cells (in solution);
- Centrifuge;
- At different / increasing speeds until chloroplast fraction obtained;
Give the function of a mitochondrion.
The site of aerobic respiration (reactions) OR
ATP is made / ADP is phosphorylated;
Give three properties of water that are important in biology.
Is a metabolite Is a solvent Has a (relatively) high heat capacity Has a (relatively) large latent heat of vaporisation / evaporation Has cohesion / hydrogen bonds between molecules;;;
Name the method she would have used to produce these sucrose solutions.
Dilution series;
0.8; 2.72 - 2.20
Explain the result for the chip in 0.8 mol dm–3 sucrose solution.
- (0.8 mol dm–3 sucrose) solution has a more negative / lower water potential than potato (cytoplasm);
OR
potato (cytoplasm) has a less negative / higher water potential than (0.8 mol dm–3 sucrose) solution; - (therefore) water moves out (of potato) into the (sucrose) solution by osmosis (so cells decrease in mass);
Species
organisms that are able to produce fertile offspring
Species richness
the number of (different) species in a community;
68% of all the fish caught in this investigation came from sample A.
A student thought this showed that sample A had a greater index of diversity than any of the other samples.
It is not possible to draw this conclusion from the given data. Give reasons why.
- Number of individuals of each species not known;
- Almost all (of sample A / the 68%) could be of the same species;
- Two / other samples have a higher number of species / higher species richness but a lower number of individuals / fish;
- Other samples may have more individuals of each species;
Suggest and explain why AZT does not destroy HIV in the body but stops or slows the development of AIDS (lines 3–4).
- Person (infected with HIV) has HIV DNA (in their DNA);
- New HIV (particles) still made;
- (AZT) inhibits reverse transcriptase;
- (AZT) stops these (new HIV particles) from forming new HIV DNA;
OR
Slows / stops replication of HIV; - Stops destruction of more / newly infected T cells;
- So immune system continues to work (and AIDS does not develop);
Suggest and explain two advantages of using HAART (lines 7–9)
- Slows / stops the development of AIDS;
- Because HIV resistant to AZT is damaged / destroyed / prevented from replicating (by other drugs);
OR - AZT continues to work as a drug;
- Because HAART prevents the spread of
AZT-resistant HIV to rest of the human population;
OR - No new HIV particles made;
- Because HAART might interfere with viral protein synthesis;
Suggest why high doses of AZT lead to muscle wastage (lines 10–11).
- (Fewer mitochondria so) less (aerobic) respiration;
2. (Muscles receive) less ATP (so waste);
