IGCSE Biology Review ?s (Extended) s.22/43

You are testing for an unknown substance. You use iodine and it turns black. What does the substance contain?

• starch

• reducing sugar

• protein

• lipids

What are two materials needed to be added to a fermenter to produce penicillin?

• protein and fat

• glucose and protein

• amino acid and fat

• glucose and ions (salts)

Why does the fermenter have a gas outflow pipe? (gas out)

• add nutrients and water

• mix the gas with the nutrients

• release gas and prevent fermenter exploding

• prevent contamination and mix nutrients with solution

State the role of haemoglobin.

Answer explanation

Transport oxygen it the blood stream.

The allele for the normal form of haemoglobin is HbA.

The allele for abnormal form of haemoglobin is HbS.

Both parents are heterozygous.

What are the parents phenotypes?

Answer explanation

Phenotype is the physical appearance.

Heterozygous means one of each.

Answer:

Both parents are carriers.

The allele for the normal form of haemoglobin is HbA.

The allele for abnormal form of haemoglobin is HbS.

Both parents are heterozygous.

What are the parents genotypes?

Answer explanation

Mom = HbA and HbS

dad = HbA and HbS

The allele for the normal form of haemoglobin is HbA.

The allele for abnormal form of haemoglobin is HbS.

Both parents are heterozygous.

What are the offsprings genotypes?

Answer explanation

Mom Dad

HbA HbS HbA HbS

Genotypes= HbAHbA, HbAHbS, HbSHbS

Describe how acid rain destroys forests.

Answer explanation

Acid rain will lower the pH of the soil.

It will damage the leaves

Affect the roots to absorb mineral ions

Damage roots reducing water uptake.

Describe the structure of th villus and its role in the alimentary canal

Answer explanation

P = lacteal that absorbs fats, fatty acid, glycerol & vitamins

T = lymphatic vessel, returns fats to blood

Q = epithelial cell, has microvilli that increases surface area for absorption;

It is also one cell thick for quick absorption

Also breaks down maltose to glucose

R = capillary, for absorption of animo acids, glucose, salts, water

Blood flow stays constant to maintain a concentration gradient.

Using the information, state the optimum length of time for efficient extraction of juices.

• 45-90 min

• 40-90 min

• 45 min

• 90 min