Photo AI
Read the following passage - AQA - A-Level Biology - Question 10 - 2023 - Paper 2
Question 10
Read the following passage. ATP is essential for muscle contraction. The concentration of ATP in skeletal muscle is approximately 5 × 10^-3 mmol g^-1. During maximu... show full transcript
Worked Solution & Example Answer:Read the following passage - AQA - A-Level Biology - Question 10 - 2023 - Paper 2
Step 1
Describe the roles of ATP in muscle contraction.
Answer
ATP plays several key roles in muscle contraction:
-
Breaking Actin-Myosin Bridges: ATP is critical for the detachment of myosin heads from actin filaments, allowing them to reset for another cycle of contraction.
-
Movement of Myosin Heads: When ATP is hydrolyzed, it provides energy that causes conformational changes in the myosin head, enabling it to pull actin filaments inward, which results in muscle contraction.
-
Calcium Ion Transport: ATP is also involved in actively transporting calcium ions back into the sarcoplasmic reticulum after muscle contraction, facilitating muscle relaxation.
Step 2
Step 3
Describe and explain how taking creatine supplements and 'carbohydrate loading' can improve performance of different types of muscle fibres during different types of exercise.
Answer
Creatine supplements increase the availability of phosphocreatine, which helps rapidly regenerate ATP during short bursts of high-intensity exercise, enhancing performance in fast-twitch muscle fibers typically used in sprinting or weightlifting.
Carbohydrate loading maximizes glycogen stores in both fast and slow-twitch muscle fibers, allowing for sustained energy release in longer-duration activities like marathons. The increased availability of glucose provides an extended energy source, which is especially beneficial during aerobic exercises.
Step 4
Suggest and explain how GLUT4 and CD36 transport proteins are beneficial during exercise.
Answer
GLUT4 transport proteins enhance glucose uptake into muscle cells during exercise, facilitating increased energy production. This is particularly important as muscle activity elevates glucose demands.
CD36 transport proteins assist in fatty acid uptake into muscle cells, providing an additional source of energy during prolonged exercise. By enabling the oxidation of fatty acids, CD36 supports endurance activities and helps spare glycogen stores.
Step 5
An increase in muscle activity causes an increase in heart rate. Describe and explain how.
Answer
The increase in muscle activity leads to a rise in carbon dioxide levels in the blood, detected by chemoreceptors. This triggers an increase in neural impulses to the cardiac center, which results in an increased heart rate. Additionally, this response helps to enhance blood flow and oxygen delivery to active muscles, ensuring that metabolic demands are met during periods of high activity.