Paper 2 Exam Questions Flashcards
Define homeostasis (3)
Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes. Homeostasis maintains optimum conditions for enzyme action and all cell functions.
Describe the function of the pituitary gland (3)
The pituitary gland in the brain is a ‘master gland’ which secretes several hormones into the blood in response to body conditions. These hormones in turn act on other glands to stimulate other hormones to be released to bring about effects.
Explain the roles of thyroxine and adrenaline in the body (4)
Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for fight or flight. Thyroxine from the thyroid gland stimulates the basal metabolic rate. It plays an important role in growth and development.
In Vitro Fertilisation (IVF) treatment can be used to help women become pregnant. Explain why IVF increases the chance of some women becoming pregnant (6)
FSH and LH are used to treat the woman to increase her chances of becoming pregnant. During IVF, FSH causes the eggs to mature. LH then causes the egg to be released. High levels of hormones cause many eggs to be matured and released. The sperm and eggs are then collected and the eggs are fertilised outside of the body, increasing the chances of fertilisation. The fertilised eggs are then given time to develop into a small ball of cells. Some are then transferred into the mothers uterus to increase the probability of one successfully implanting.
Explain how the body would respond if too much insulin is injected into the body (4)
When an excess amount of insulin gets injected into the body, the blood glucose level decreases to a dangerous amount. When the blood glucose level is too low, the pancreas releases glucagon. Glucagon triggers liver cells to convert glycogen stores back into glucose. This glucose is then released into the blood to regulate the blood glucose level and maintain the balance between insulin and glucagon in the body.
Describe the interaction of hormones in the menstrual cycle (6)
In the first stage of the menstrual cycle, FSH is released by the pituitary gland. It then travels in the blood to the ovaries where it causes an egg to mature. Simultaneously, FSH triggers the ovaries to make oestrogen which causes the uterus lining to become thick. Oestrogen also inhibits the release of FSH. The pituitary glands then release LH which triggers ovulation. An egg is then released which stimulates the production of progesterone from the ovaries. Progesterone stops the pituitary gland from releasing LH and FSH to prevent the maturing or release of any more eggs. Progesterone also maintains the uterus lining, keeping it thick so that the egg can implant. If fertilisation does not take place, the level of progesterone falls. The uterus lining and the egg are released in the form of a period.
