Q BANK

Explai how meiosis can produce a gamete with one extra chromosome

1. Non-disjunction

2. Sister chromosomes cannot separate/ homologous pairs of chromosomes cant separate

3. Both chromosomes are pulled to one pole of the cell

Describe process of bacteria cell dividing

1. Binary fission

2. Replication of DNA

3. Division of cytoplasm to produce 2 daughter cells

4. Each with single copy of DNA

Describe the action of dipeptidase and explain their importance

1. Hydrolyse peptide bonds to release amino acids

2. Amino acids can cross cell membrane

3. Ensures maximum yield from protein breakdown

Explain why damage to cells lining the ileum reduces the absorption of products of digestion and why this reduces the absorption of water

• decreases surface area

• Decreases the water potential in ileum/lumen or increase water potential in cells

• Water moves out of cells into ileum by osmosis

Describe how higher concentration of salts in blood leads to build up of tissue fluid

1. Lower water potential of tissue fluid

2. Less water returns to capillary by osmosis (at venule end)

Or

3. Higher blood pressure/volume

4. More fluid forced out (at arteriole end)

How can asthma cause drop in mean FEV

• muscle walls of bronchioles contract

• Secrete more mucus

• Decreased diameter of airways

• Reduced flow of air

Explain how low FEV1 value could make walking up the stairs difficult

• less CO2 removed from lungs

• Less oxygen taken up/ diffuses into blood

• Less aerobic respiration

Explain the difference in the rate at which air is breathed out between a healthy person and someone wth emphysema

• decreased surface area of alveoli so slower rate of gas exchange

• Loss of elastic tissue to stretch and recoil

• Exhalation is difficult

• Increased breathing rate to supply more oxygen

Why did the student soak garlic root tips in HCl before staining

• hydrolyse/ break down cellulose/cell wall

• Allows the stain to diffuse in

Suggest 2 explanations why other students in class obtained different mitotic indices

• garlic roots are different ages

• Cells undergo mitosis at different rates/times

• Root tips from different garlic plants

• Single field of view not representative of a root tips

explain why student used only first 5 mm of an onion rot

• where dividing cells are found/ mitosis occurs

• No dividing cells further away from the tip

Describe a method this student could use to prepare colour standards and use them to give data for total anthocyanin extract ( no colorimeter)

• use known concentrations of pigment/ solvent

• Prepare serial dilutions

• Compare with colour standards to give concentration