2012 Unit 2 June Flashcards
What is an organ?
• A group of tissues;
Describe how carbon dioxide in the air outside a leaf reaches mesophyll cells inside
the leaf.
- (Carbon dioxide enters) via stomata;
- (Stomata opened by) guard cells;
- Diffuses through air spaces;
- Down diffusion gradient
Suggest how the faster rate of growth may increase profit for a farmer
• Beet/ harvested earlier;
Describe and explain how selection will have affected the genetic diversity of sugar
beet.
• (Diversity) reduced / smaller gene
pool
• As alleles have been chosen/
rejected;
Name the monomers that form a cellulose molecule
• Beta glucose
Explain one way in which the structure of cellulose is linked to its function
- H-bonds / micro/macro fibrils /fibres;
* Strength / rigidity / inelasticity;
Mitosis is important in the life of an organism. Give two reasons why
- Growth
- Replace cells
- Genetically identical cells;
- .Asexual reproduction /cloning
DNA is a polymer. What is the evidence from the diagram that DNA is a polymer?
• .Repeating nucleotides / monomer
/molecules;
The gene for this polypeptide contains more than this number of bases.
Explain why
• Some regions of the gene are non-coding
/ introns / start/stop code
Name one other taxonomic group to which all members of the Apodiformes belong.
• Kingdom / phylum / class;
Name the taxonomic group between order and genus
• Family;
Explain how the standard deviation helps in the interpretation of these data
• Shows the spread of the data / how
data varies
• Low SD means results more reliable /
repeatable
Use your knowledge of transpiration to explain the changes in the rate of flow in the
xylem shown in the graph.
- Stomata open;
- Transpiration highest around midday;
- Middle of day warmer / lighter;
- (Increased) tension/water potential gradient
- Cohesion (between water molecules);
Explain why the values for the pressure in the xylem are negative.
• (Inside xylem) lower than atmospheric
pressure / (water is under) tension
Explain the difference in thickness between the pulmonary artery and the pulmonary
vein.
• High pressure / smoothes out blood
flow
• Artery wall contains more
collagen
The thickness of the aorta wall changes all the time during each cardiac cycle.
Explain why
• (Aorta wall) stretches; • Because ventricle/heart contracts / systole / pressure increases; • (Aorta wall) recoils; • Because ventricle relaxes / heart relaxes • Maintain smooth flow / pressure
Which of the three blood vessels shows the greatest variation in wall thickness?
Explain your answer.
- Aorta
* Largest Standard deviation
Describe how tissue fluid is formed and how it is returned to the circulatory system.
Formation • High blood / hydrostatic pressure / pressure filtration; • Forces water / fluid out • Large proteins remain in capillary Return • Low water potential in capillary / blood; • Due to (plasma) proteins; • Water enters capillary / blood; • (By) osmosis;
The flasks were incubated at 35 oC. Suggest why they were incubated at this
temperature.
• Fastest rate of growth
• Optimum
temperature for enzymes
The scientist put the same volume of bacterial culture into each flask. Explain why.
• Same amount of bacteria
What was the purpose of the control flask?
• To show that only the antibiotic has an
effect
Give two ways in which a bacterium could become resistant to an antibiotic.
- Mutation
* Horizontal transmission
The people chosen to be included in the survey were all of a similar age. Suggest why
• Age affects immune system
Some dentists recommend a course of antibiotics when someone has a tooth
extracted. Does the information in parts (b), (c) and (d) support this recommendation?
Explain your answer.
- Antibiotic reduces number of bacteria
- (Survivors have) resistant gene/
- (Resistant bacteria) reproduce
