bio paper 2

• Leaves with large surface area


  Allow maximum absorption of sunlight
• Chloroplasts


  Have lots of chlorophyll in them to trap the energy of sunlight. They can move away or towards the light within the cell.
• Thin leaves


  Means that carbon dioxide does not have far to diffuse before reaching photosynthesising cells
• Spongy mesophyll cells


  Are irregularly shaped and have large air spaces between them that allow gases to diffuse throughout the leaf easily.
• Xylem vessels


  A network of these supply the water to the leaf tat is needed for photosynthesis
• Waxy cuticle


  prevents water loss, and prevents microorganisms and water from entering the leaf. Can be thick enough to become self cleaning.
• Epidermal cells


  Holds the leaf together and protect the cells inside. They are transparent to allow light to pass through them easily.
• Chlorophyll


  Green pigment found in chloroplasts that traps the energy of sunlight needed for photosynthesis
• Guard cells


  Can control the opening and closing of the stomata to allow carbon dioxide to diffuse in and water vapour and oxygen to diffuse out.
• Xylem


  Dead tissue that carries water and dissolved mineral salts from the roots of a plant to its leaves. Thickened with lignin.
• Phloem


  Living tissue that carries sucrose and amino acids throughout a plant
• Vascular bundle


  A strand of vascular tissues (both xylem and phloem) in a stem or leaf.
• lignin


  A chemical that hardens the cell walls of plants
• Sieve tubes


  A column of phloem cells in a plant
• Sieve plates


  Porous end walls that allow fluid to flow between cells along the phloem (sieve tube)
• Osmosis


  Diffusion of water molecules through a partially permeable membrane from an area of higher concentration to an area of lower concentration
• Root hair cells


  Specialised cells with large surface area. Water enters these cells by osmosis and mineral salts enter by active transport
• Diffusion


  Net movement of particles from an area of higher concentration to an area of lower concentration.
• Active transport


  The movement of particles from an area of low concentration to an area of high concentration. This process uses energy.
• Transpiration


  The process by which plants release water vapor through their leaves
• Plasmolysed


  When plants cells do not contain enough water, and the cell membrane pulls away from the cell wall
• Turgid


  Plant cells are swollen because they have absorbed water
• Potometer


  An instrument used for measuring the rate of water uptake of a plant due to transpiration.
• Translocation


  The movement of sucrose and amino acids up and down the plant
• photosynthesis


  a series of enzyme-catalysed reactions carried out by the green parts of plants to produce glucose. It requires carbon dioxide, water and requires energy transferred by light.
• chloroplast


  a green disc containing chlorophyll found in plant cell. This is where the plant makes glucose through photosynthesis.
• endothermic reaction


  a type of reaction in which energy from the surroundings is transferred to the products eg photosynthesis.
• starch


  insoluble storage molecule (polymer) in plants made of many glucose molecules.
• palisade cells


  tall, column-shaped cell near the upper surface of a plant leaf where most photosynthesis happens
• stomata


  tiny pores in a leaf, which open, allow oxygen and carbon dioxide to diffuse into and out of the leaf.
• guard cells


  cells that surround the stomata to open and close them
• limiting factor


  a single factor that when in short supply can limit the rate of the process, such as photosynthesis.
• inverse square law


  the relationship between light intensity and the distance from the light source.
• transpiration


  The process by which plants release water vapour through their leaves
• Hormone


  A chemical messenger, secreted by an endocrine gland, that brings about a response in target cells
• Pituitary gland


  An endocrine gland found in the brain. It secretes FSH and LH
• Oestrogen


  Produced by the ovaries. Controls female puberty and also the build up of the lining of the uterus during the menstrual cycle.
• Testosterone


  Male sex hormone. Produced by the testes controls the development of secondary sexual characteristics during puberty and also the production of sperm.
• Menstrual cycle


  A cycle in women that lasts around 28 days during which ovulation takes place
• Follicle stimulating hormone (FSH)


  Produced by the pituitary gland that causes an egg to mature in the follicle.