bio p2

• carbon dioxide + water —> glucose + energy
• during photosynthesis energy from the sun is used to make glucose. some of the glucose is then used to make larger molecules to help the plant grow.
• photosynthesis is an endothermic reaction as it takes in energy from the environment
• light intensity, carbon dioxide and temperature can affect the rate of photosynthesis
• root hairs in plants take in minerals and water.
• phloem tubes in plants transport food. they are made of living cells. phloem tubes trsnsport these food substances around the plant. this process is called transolocation
• translocation uses energy from respiration to move sucrose from the leaves to the rest of the plant
• xylem tubes take water up the plant
• xylem tubes are made of dead cells. the cells contain a material called lignin and makes it stronger. xylem tubes carry water from the roots to the leaves
• the movement of water from the roots through the xylem and out of the leaves is called the transpiration stream
• transpiration is caused by the evaporation and diffusion of water from a plants surface. water evaporates from the leaves and diffuses into the air. this creates a slight shortage of water in the leaf. this in turn means more water is drawn from the roots
• stomata are involved in transpiration. stomata are tiny pores on the surface of the plant. they’re mostly found on the lower surface of the leaf. stomata can open and close.
• when the stomata is open carbon dioxide and oxygen can diffuse in and out of the leaf. water vapour can also diffuse in and out of the leaf during transpiration
• stomata are surrounded by guard cells. these change shapes to control the size of the stomata
• transpiration rate is affected by light intensity, temperature, air flow
• hormones are chemical messengers sent in the blood. hormones are chemicals released by glands. these glands are called endocrine glands
• hormones only affect particular cells in particular organs
• the pituitary glands release lots of different hormones. these hormones act on other glands making them release hormones
• thyroid glands produces thyroxine. thyroxine regulates things like heart rate and temperature
• ovaries produces oestrogen which is involved in the menstrual cycle
• adrenal glands produce adrenaline. adrenaline prepares you for stressful situations
• testes produce testosterone which controls puberty and sperm production in males
• the pancreas produces insulin. insulin controls the blood glucose level
• neurones have very fast action and act for a very short time
• hormones are a slower action and act for a long time
• the menstrual cycle had four stages
• stage 1 of the menstrual cycle is when the mentruation (bleeding) starts. the lining of the uterus breaks down and is released
• stage 2 of the menstrual cycle is when the uterus lining is built up from day 4 to day 14. it becomes a thick spongy layer full of blood vessels. it’s now ready for a egg to be there
• stage 3 of the menstrual cycle is when an egg develops and is released from the ovary at about day 14. this is called ovulation
• stage 4 of the menstrual cycle is the when the lining is then maintained until day 28
• oestrogen is released by the ovaries. it causes the lining of the uterus to thicken and grow. a high level stimulates the release of a hormone which causes ovulation
• progesterone is released by the corpus luteum after ovulation. it maintains the lining of the uterus. it prevents the release of hormones which cause egg development and ovulation. when the progesterone levels falls the uterus lining breaks down.
• contraceptive are things that prevent pregnancy
• barrier methods can also be used to prevent pregnanc. e.g. condoms, female condoms or diaphragms
• homeostasis means keeping the right conductions inside your body so that everything works properly
• to keep your body conditions steady your body needs to respond with changes that happen outside your body and changes that happen inside
• insulin helps to control blood glucose concentration. eating carbohydrates puts glucose into the blood. glucose removed from the blood by cells. when you exercise a lot more glucose is removed from the blood
• changes in blood glucose are monitored and controlled by the pancreas. if blood glucose concentration gets too high the pancreas releases the hormone insulin.
• insulin converts glucose into glycogen. glycogen is stored into the liver and muscle cells. so insulin removes glucose from the blood
• in type 1 diabetes the pancreas stops making insulin. this means the persons blood glucose can rise to a level that can kill them.