B2 notes
- Created by: loupardoe
- Created on: 14-05-16 16:36
parts of cells
nucleus- contains genetic material that controls the activities of the cell
cytoplasm- gel-like substance where most of the chemical reactions happen. Contains enzymes that control the chemical reactions
cell membrane- holds the cell together and controls what goes in and out
mitochondria- where most of the reactions for respiration take place
ribosomes- where proteins are made in the cell
cell wall- made of cellulose. supports the cell and strengthens it
chloroplasts- where photosynthesis occurs. contain chlorophyll
permanent vacuole- contains cell sap
specialised cells
yeast- has a nucleus, cytoplasm, cell membrane and a cell wall
bacteria- cell membrane, cytoplasm, cell wall, genetic material
palisade leaf cells-
- chloroplasts at top near light
- tall=big surface area to absorb carbon dioxide
- thin to put lots in at top of leaf
guard cells
- kidney shape opens and closes the stomata
- fill with water, go plump, opens stomata for gas exchange
- lose water, go flaccid, stomata closes
- thin outer walls, thick inner walls
- sensitive to light, close at night
red blood cells
- concave shape=big surface area for absorbing oxygen. also helps to pass smoothly through capillaries
- packed with haemoglobin
- have no nucleus
sperm cells
- carry male DNA to female DNA
- long tail and streamlined head to swim
- mitochondria to provide energy
- enzymes to digest the egg cell membrane
egg cells
- carry female DNA, nourish developing embryo
- contains food reserver
- eggs' membrane changes structure when sperm fuses with egg. stops more sperm getting in
diffusion
- the spreading out of particles from an area of high concentration to an area of low concentration
- the bigger the difference, the faster the diffusion rate
- dissolved substances can move in and out of cells by diffusion
- only very small molecules are let through
cell organisation
differentiation- the specialisation of a cell. occurs during the development of a multicellular organism
tissue- a group of similar cells that work together to carry out a particular function
organ- a group of different tissues that work together to perform a certain function
organ system- a group of organs working together to perform a particular function
Plant structure and photosynthesis
parts of leaves
- mesophyll tissue- where photosynthesis occurs
- xylem and phloem- transport things
- epidermal tissue- covers plant
equation for photosynthesis- carbon dioxide + water (sunlight + chlorophyll) = glucose and oxygen
- photosynthesis produces glucose
- happens inside the chloroplasts
- chlorophyll absorbs sunlight, converts carbon dioxide and water into glucose and oxygen
- happens in leaves of all green plants
1) sunlight beating down on the leaf provides energy
2) chlorophyll contained in chloroplasts
3) water reaches cells via xylem
4) carbon dioxide diffuses into the leaf
rate of photosynthesis
limiting factor- stops photosynthesis from happening faster
at night light = limiting factor
in winter temperature = limiting factor
otherwise carbon dioxide is the limiting factor
1) light provides energy for photosynthesis
2) as the light level is raised, the rate of photosynthesis increases, but only to a certain point
3) beyond that it won't make any difference because then either temperature or carbon dioxide will…
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