paper 1 biology

• osmosis is the movement of water molecules through a partially permeable membrane from high water concentration to low water concentration
• white blood cells produce antibodies
• red blood cells are concave disc shaped and carry haemoglobin throughout the body
• benign tumours are non-cancerous
• malignant tumours are cancerous
• chromosomes are coiled up lengths of DNA molecules
• multicellular organisms use mitosis to grow or replace damaged cells
• cancer is caused by uncontrolled cell division
• phagocytosis is where white blood cells engulf foreign cells and digest them
• amylase breaks down starch into glucose
• protease breaks down proteins into amino acids
• lipase breaks down lipids into fatty acids and glycerol
• bile neutralises the stomach acids because it is alkaline
• bile is secreted by the liver and stored in the gall bladder
• bile emulsifies fats to increase the surface area for the lipase to work on
• photosynthesis: carbon dioxide + water -> glucose + oxygen
• glucose in plants is used for respiration
• photosynthesis takes place in the chloroplasts, while the chlorophyll absorb the light
• aerobic respiration: glucose + oxygen -> carbon dioxide + water
• anaerobic respiration: glucose -> lactic acid
• the phloem transports food substances from the leaves to other parts of the plant in a process called translocation
• the xylem carries water and mineral ions from the roots to the stem and leaves, this movement of water through the xylem and out of the leaves is called the transpiration stream
• xylem is made out of dead cells joined end to end with no walls between them and a tube down the middle. they are strengthened with a material called lignin
• phloem is made of columns of elongated living cells with small pores in the end walls to allow cell sap to flow through
• transpiration is the loss of water from the plant. there is more water inside the plant than there is in the surroundings, so the water escapes through the leaves by diffusion and evaporates from the plant's surface
• the higher the light intensity, the faster the transpiration rate
• the higher the temperature, the faster the transpiration rate
• the guard cells control the opening and closing of stomata for gas exchange
• differentiation is the process by which a cell changes to become specialised for its job
• muscle cells have lots of mitochondria to generate the energy needed for contraction
• stem cells are found in bone marrow and early human embryo
• stem cells are undifferentiated cells that divide and differentiate into many different kinds of cell
• stem cells can be used to make plants grow in certain ways, e.g. disease resistance
• in plants, stem cells are found in the meristem
• prokaryotic cells replicate by binary fission
• active transport is the movement of particles from a low concentration to a high concentration, root hair cells use this to take in minerals and water from the soil
• first, drugs are tested on human cells and tissues in the lab. second, the drugs are tested on live animals. finally, the drugs are tested on human volunteers in a clinical trial if it has passed all the tests.
• monoclonal antibodies can be used to treat cancer as they only target specific antigens not killing surrounding healthy cells. however, they come with many side effects
• plants need nitrates to make proteins for growth
• plants need magnesium ions to make chlorophyll, which is needed for photosynthesis