Q: A researcher is using the Hardy-Weinberg equation to study a population. If the frequency of a recessive allele ($$q) is 0.4$$, what is the expected frequency of heterozygotes in the population?

$$2pq = 2 \times 0.6 \times 0.4 = 0.48$$

Question 1

Which of the following best describes the role of water as a solvent in biological transport systems?

Accepted Answer

Water's dipole nature enables it to dissolve ionic and polar substances, facilitating transport in organisms.

Question 2

A student is investigating the effect of temperature on the rate of an enzyme-catalyzed reaction. Which mathematical approach should the student use to determine the initial rate of reaction from their data?

Accepted Answer

Draw a tangent to the curve at the origin and calculate its gradient using $$	ext{slope} = \frac{\Delta y}{\Delta x}.$$

Question 3

Which of the following statements about the structure and function of arteries is correct?

Accepted Answer

Arteries have thick muscular and elastic walls to withstand high pressure from the heart.

Question 4

A patient has a genetic disorder caused by a substitution mutation in a gene. Which of the following outcomes is most likely?

Accepted Answer

The mutation may result in a different amino acid, potentially altering protein function.

Question 5

Which process is responsible for the movement of oxygen from the alveoli into the blood in the lungs?

Accepted Answer

Simple diffusion down a concentration gradient

Question 6

A researcher is using the Hardy-Weinberg equation to study a population. If the frequency of a recessive allele ($$q) is 0.4$$, what is the expected frequency of heterozygotes in the population?

Accepted Answer

$$2pq = 2 	imes 0.6 	imes 0.4 = 0.48$$

Question 7

Which of the following best explains why high-density lipoproteins (HDLs) are considered 'good' cholesterol?

Accepted Answer

HDLs remove cholesterol from tissues and transport it to the liver for excretion, reducing cardiovascular risk.

Question 8

Which of the following is a key feature of the fluid mosaic model of cell membranes?

Accepted Answer

Phospholipids and proteins can move laterally within the layer, allowing membrane flexibility.

Question 9

A scientist is analyzing the biodiversity of two habitats using the index of diversity formula $$D = \frac{N(N-1)}{\sum n(n-1)}. If $$Habitat A has a higher $$D$$ value than Habitat B, what does this indicate?

Accepted Answer

Habitat A has greater biodiversity than Habitat B.

Question 10

Which of the following best describes the role of the loop of Henle in the mammalian kidney?

Accepted Answer

It acts as a countercurrent multiplier to concentrate urine by reabsorbing water.

Question 11

During an investigation, a student uses a light microscope to observe onion cells. Which of the following steps is essential for improving the visibility of the cell nucleus?

Accepted Answer

Staining the cells with iodine solution.

Question 12

Which of the following is a correct statement about the Bohr effect in haemoglobin?

Accepted Answer

The Bohr effect describes how increased carbon dioxide concentration decreases haemoglobin's affinity for oxygen.

Question 13

A population of beetles is studied over several generations. Which process is most likely to lead to the formation of a new species?

Accepted Answer

Reproductive isolation leading to accumulation of genetic differences.

Question 14

Which of the following best describes the function of restriction endonucleases in gene technology?

Accepted Answer

They cut DNA at specific sequences, allowing gene insertion.

Question 15

A patient is given a statin as part of their treatment for cardiovascular disease. What is the primary action of statins?

Accepted Answer

They inhibit cholesterol synthesis in the liver, reducing blood cholesterol levels.

Question 16

Which of the following is a real-world application of the polymerase chain reaction (PCR) in biology?

Accepted Answer

Amplifying DNA samples for forensic analysis.

Question 17

A scientist is studying the effect of a new antibiotic on bacterial growth. Which method would best allow her to determine the exponential growth rate constant of the bacteria?

Accepted Answer

Measuring the optical density of the culture at regular intervals and plotting $$\ln(N)$$ versus time.

Question 18

Which of the following best explains why scientific models of climate change have limitations?

Accepted Answer

They are based on incomplete data and assumptions about future variables.

Question 19

Which of the following is a key ethical consideration in the use of stem cells for medical therapies?

Accepted Answer

The source of stem cells and the potential destruction of embryos.

Pearson Edexcel International Advanced Level Biology: Specification Study Guide

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