2013 Unit 2 Jan Flashcards
Name the type of reaction that would break down these carbohydrates into their
monomers.
• Hydrolysis
Give one feature of starch and explain how this feature enables it to act as a storage substance.
Coiled/helical/spiral
• So compact/tightly packed/can fit lots in a small space
Insoluble
• So no osmotic effect/does not leave cell/does not effect water potential
Large molecule
• So does not leave cell/contains large number of glucose units;
Branched chains
• So easy to remove glucose
An arteriole is described as an organ. Explain why.
• Made of (different) tissues / more than one tissue;
An arteriole contains muscle fibres. Explain how these muscle fibres reduce blood flow
to capillaries.
- Muscle contracts
* (Arteriole) narrows/constricts/reduces size of lumen/vessel / vasoconstriction;
A capillary has a thin wall. This leads to rapid exchange of substances between the
blood and tissue fluid. Explain why.
• Short diffusion distance/pathway;
Blood flow in capillaries is slow. Give the advantage of this.
• (More) time for exchange/diffusion (of substances);
Kwashiorkor is a disease caused by a lack of protein in the blood. This leads to a
swollen abdomen due to a build up of tissue fluid.
Explain why a lack of protein in the blood causes a build up of tissue fluid.
- Water potential in capiliary not as low/is higher/less negative/water potential gradient is reduced
- Less/no water removed (into capillary);
- By osmosis (into capillary);
All modern cheetahs are thought to have descended from a single female. This female
was part of a small population that survived an ice age a long time ago that killed
almost all cheetahs. After the ice age, the number of cheetahs increased.
Use this information to explain what is meant by a genetic bottleneck.
- Drop in population / many killed / only single female left;
- Idea of reduced/low genetic variation/diversity / reduction in (variety of) alleles / smaller gene pool;
The fertility of cheetahs is low. The proportion of abnormal sperm cells produced is
higher in cheetahs than in other members of the family Felidae. Suggest an
explanation for this.
- Mutation affecting sperm cell or production (in small population);
- Errors during meiosis;
- Inbreeding / closely related cheetahs breed;
- High chance of inheriting allele / high frequency of allele (in the population)
What is intraspecific variation?
• Variation / differences within the same/a species;
Give two precautions the students should have taken when setting up the potometer to
obtain reliable measurements of water uptake by the plant shoot.
- Ensure airtight / ensure watertight;
- Cut shoot under water;
- Cut shoot at a slant
- Dry off leaves;
- Insert into apparatus under wate
- Ensure no air bubbles are present;
- Shut tap
- Note where bubble is at start / move bubble to the start position;
A potometer measures the rate of water uptake rather than the rate of transpiration.
Give two reasons why the potometer does not truly measure the rate of transpiration.
- Water used for support/turgidity;
- Water used in photosynthesis;
- Water produced in respiration;
- Apparatus not sealed/’leaks’;
A mutation in the gene coding for enzyme B could lead to the production of a
non-functional enzyme. Explain how.
- Change in base sequence (of DNA/gene);
- Change in amino acid sequence / primary structure (of enzyme);
- Change in hydrogen/ionic/ disulphide bonds;
- Change in the tertiary structure/active site (of enzyme);
- Substrate not complementary/cannot bind (to enzyme / active site) / no enzyme-substrate complexes form;
Suggest one ethical argument for maintaining biodiversity.
• We should maintain biodiversity to prevent extinction /loss of populations/ reduction in populations /loss of habitats / save organisms for future generations
Suggest one economic argument for maintaining biodiversity.
- Medical / pharmaceutical uses
- Commercial products
- Tourism
- Agriculture
- Saving local forest communities;
