Blood glucose concentration in the human body needs to be kept within the normal range - AQA - GCSE Biology Combined Science - Question 5 - 2022 - Paper 2

A: Glucagon B: Insulin

After a meal, blood glucose concentration rises due to the intake of carbohydrates.

• Insulin is secreted by the pancreas, which promotes the uptake of glucose by liver and muscle cells. It allows glucose to be converted to glycogen for storage.

• This lowers blood glucose levels back to normal. If the blood glucose levels drop too low, the secretion of glucagon occurs. Glucagon stimulates the breakdown of glycogen back into glucose in the liver, releasing glucose into the bloodstream.

• The balance between insulin and glucagon maintains blood glucose levels within the normal range for approximately 3 hours after eating.

Injecting Follicle Stimulating Hormone (FSH) stimulates the maturation of several ova in the ovaries. This prepares multiple eggs for potential fertilization. Following this, injecting Luteinising Hormone (LH) triggers ovulation, allowing an egg to be released from its follicle. Thus, the combination of FSH followed by LH increases the chances for successful fertilization.

The remaining steps in In Vitro Fertilisation (IVF) include:

• Collection of mature eggs from the ovaries.
• The eggs are then fertilized with sperm in a laboratory environment.
• The resulting embryos develop in the lab for several days.
• Healthy embryos are selected and inserted into the uterus to attempt implantation.

1. Type of Division: Sperm cells are formed through meiosis, leading to four genetically different cells, while liver cells divide through mitosis, resulting in two genetically identical cells.

2. Chromosome Number: Sperm cells contain 23 chromosomes (haploid), while liver cells contain 46 chromosomes (diploid).

3. Function: Sperm cells are reproductive cells that facilitate fertilization, whereas liver cells are somatic cells that perform metabolic functions in the body.