paper 2 Flashcards
how are root hair cells adapted
Plants absorb water from the soil by osmosis. They absorb mineral ions by active transport, against the concentration gradient. Root hair cells are adapted for taking up water and mineral ions by having a large surface area to increase the rate of absorption. They also contain lots of mitochondria, which release energy from glucose during respiration in order to provide the energy needed for active transport.
what is transpiration
When the plant opens its stomata to let in carbon dioxide, water on the surface of the cells of the spongy mesophyll and palisade mesophyll evaporates and diffuses out of the leaf. This process is called transpiration.
what is a hormone
A hormone is a chemical substance, produced by a gland and carried by the blood, which alters the activity of specific target organs (and is then destroyed by the liver).
Different hormones affect different organs or cells.
Talk about the menstrual cycle
The menstrual cycle is a recurring process that takes around 28 days. During the process, the lining of the uterus is prepared for pregnancy. If implantation of the fertilised egg into the uterus lining does not happen, the lining is then shed. This is known as
menstruation
.
what are the hormones in the menstrual cycle
Several hormones are involved in the menstrual cycle of a woman:
follicle stimulating hormone (FSH) causes the maturation of an egg in the ovary
luteinising hormone (LH) stimulates the release of the egg
oestrogen is involved in repairing and thickening the uterus lining, progesterone maintains the uterine lining
what is type 1 diabities
Type 1 diabetes is a disorder in which the pancreas fails to produce enough insulin. This can be detected from an early age. It is characterised by uncontrolled high blood glucose levels and it can be controlled by injecting insulin.
People with type 1 diabetes have to monitor their blood sugar levels throughout the day. Their levels of physical activity and their
diet affect the amount of insulin needed.
They can help to control their blood glucose level by being careful with their diet, and eat foods that will not cause large increases in blood sugar level, and by exercising, which can lower blood glucose levels due to increased respiration in the muscles.
what is type 2 diabetes
In type 2 diabetes the person’s body cells no longer respond to insulin produced by the pancreas. It is more common in older people. It can be controlled by a carbohydrate controlled diet and an exercise regime. Carbohydrate is digested into glucose, which raises the overall blood glucose level. There is a correlation between rising levels of body mass in the general population and increasing levels of type 2 diabetes.
what is thyroxine
Thyroxine is produced from the
thyroid gland, which stimulates the metabolic rate. It controls the speed at which oxygen and food products react to release energy for the body to use. Thyroxine also plays an important role in growth and development. Its levels are controlled by negative feedback.
what is something that happens when we get too hot
Sweat glands in the dermis release more sweat onto the surface of the epidermis. The sweat evaporates, transferring heat energy from the skin to the environment.
what is osmoregulation
Osmoregulation is the control of water levels and mineral ions (salt) in the blood. Water levels and mineral ions in the blood are controlled to keep the concentrations the same inside the cells as around them. This protects cells by stopping too much water from entering or leaving them by osmosis.
what is ADH
Different amounts of ADH are released into the bloodstream according to the concentration of water in the blood plasma. ADH is released by the pituitary gland when the blood is too concentrated and it causes the kidney tubules to become more
permeable. This allows more water to be reabsorbed back into the blood during selective reabsorption.
If a person has consumed a large volume of water and has not lost much as sweat, too much water might be detected in the blood plasma. If this occurs, less ADH will be released, which results in less water being reabsorbed and a dilute and larger volume of urine will be produced.
What is dialysis
Unfiltered blood that is high in urea is taken from a blood vessel in the arm, mixed with blood thinners or an anti-coagulant to prevent clotting, and pumped into the dialysis machine. Inside the machine the blood and dialysis fluid are separated by a partially permeable membrane the blood flows in the opposite direction to dialysis fluid, allowing a concentration gradient to exist and exchange of substances to occur.
