2011 Unit 1 June Flashcards
Lactose, galactose and monosaccharide X are all reducing sugars.
After the lactose has been broken down there is a higher concentration of reducing
sugar. Explain why.
• 2 sugars produced
A high concentration of galactose slows down the breakdown of lactose by lactase.
Use your knowledge of competitive inhibition to suggest why.
• Galactose is a similar shape/structure to lactose
People who are lactose intolerant are not able to produce the enzyme lactase.
Explain why these people get diarrhoea when they drink milk containing lactose.
- Low / decreased water potential (in gut);
* Water enters gut / lumen / leaves cells by osmosis;
Some people have used the graph to conclude that a high percentage of fat in the diet
causes breast cancer. Evaluate this conclusion.
- Positive correlation;
- But correlation does not show causation
- Evidence against positive correlation
How should the students make sure that the pH of the protease solution did not
change?
• Use buffer
Use the diagram to describe the effect of pH on the activity of this protease
• Works best at pH 6
The two people were breathing out during the time shown. What evidence in the table
supports this statement?
• Volume (of air in lungs) decreases;
Emphysema reduces the efficiency of gas exchange in the lungs. Explain why.
- Alveoli break down / collapse
- Epithelium walls thicken;
- Reduced surface area / increased diffusion pathway
- (So) less diffusion;
- Elastic (tissue) / not recoiling / loss of elasticity
- Reduced flow rate
- Reduced diffusion or concentration gradient;
Give two ways in which active transport is different from facilitated diffusion.
- Uses energy / ATP;
- Against concentration gradient
- Does not use channel proteins / only uses carrier proteins;
The scientists used a control group in this trial. Explain why
• To see the effect of the drug
Suggest how the control group would have been treated.
- Placebo
* (Otherwise) treated the same;
Describe the effect of taking the drug on acid secretion.
• Decrease for 3 hours;
The maximum pressure in the ventricle is much higher than that in the atrium.
Explain what causes this.
- (Ventricle has) thick wall / more muscle
* So contractions are stronger / harder
Explain how atheroma can lead to a heart attack
- Coronary artery / vessel is blocked/narrows;
- Restricts oxygen supply to heart muscle
- Prevents respiration / ATP production / or (heart) muscle / tissues/cells die
Explain what is meant by an antigen.
- Protein on (surface of) chlamydia;
* That initiates an immune response
After an infection with chlamydia, cells of the immune system of the mice may attack
the heart muscle cells (lines 7-8). Explain why.
- Antibodies/memory cells against chlamydia (protein/antigen) are present;
- Protein on heart (muscle) similar to chlamydia protein/antigen;
- T cells / antibodies (attack heart muscle cells
Some scientists have suggested that people should be vaccinated to prevent infection
by chlamydia. Evaluate this suggestion.
FOR
• Prevents / reduces heart disease/attacks
• Cheaper to vaccinate than treat heart disease
AGAINST
• Vaccination costly;
• Vaccine could cause heart disease or immune response against heart
Describe how these phagocytic white blood
cells destroy bacteria.
- Phagocyte recognise antigens on bacteria as foreign;
- Engulf bacteria;
- Bacteria in vacuole
- Lysosome fuses with
- Bacteria digested / hydrolysed
The epithelial cells that line the small intestine are adapted for the absorption of
glucose. Explain how.
- Microvilli;
- Large/increased surface area;
- Many mitochondria;
- Mitochondria produce ATP / release or provide energy (for active transport);
- Carrier proteins for active transport;
- Channel / carrier proteins for facilitated diffusion;
- Co-transport of sodium (ions) and glucose
- Membrane-bound enzymes digest disaccharides / produce glucose
