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  • Created by: Paigeeeee
  • Created on: 12-05-13 12:20

B2 overview


human cells

cell membrane - controls substances passing in and out

nucleus - controls the activity in the cell

cytolpasm - where most chemical reactions take place

mitochondria - energy released by respiration here

ribosomes - where protein synthesis takes places

Plant cells

cell wall - to strengthen the cell

vacuole - filled with cell sap

chloroplasts - contain chlorophyll which absorbs light energy to make food

Other cells


cytoplasm, no nucleus, cell wall, cell membrane

fungus yeast

cytoplasm, nucleus, cell wall, cell membrane


is the net movement of particles in a substance which goes from an area of high concentration to an area of low concentration. larger the difference in concentration, the faster the rate of diffusion. Co2 diffuses from the blood into the lungs in order to be exhaled.


group of cells which have a similar function and structure. cells differentiate in order to be able to carry out a specific function. Epithelial tissue which covers parts of the body, glandular tissue which secretes things such as enzymes, digestive juices and hormones. Muscle tissue, enables the muscle to contract to bring about movement.


made up of different types of tissues. For example, the stomach is made up of muscle tissue which churns the contents of the stomach, glandular tissue to secrete enyzmes such as protease and epithelial tissue to cover the surfaces of the stomach.

Organ Systems

digestive system includes salivary glands, small intenstine, stomach, large intestine, liver. Salivary glands and pancreas secrete enzymes to catalyse the breakdown of foods. Stomach churns food, goes into small intestine, large intestine water is removed from insoluble foods to produce faeces.

excretory system includes the kidneys.

Plant Organs

stem, leaves, roots.

Plant tissues

Epidermis, xylem, phloem, mesophyll.

Epidermis covers the plant, xylem transports water and sugar around the plant, phloem transports ---- DONT KNOW ABOUT PLANT TISSUES, mesophyll is a spongy layer with gaps to enable carbon dioxide and oxygen to pass in and out.


co2 + water --(light, chlorophyll)--> o2 and glucose

Light from the sun, carbon dioxide from the air, water from the soil, chlorophyll in chloroplasts in the leaves.

How plants use glucose

store it as insolube starch in the stem leaves or roots. used in respiration to provide energy. used for growth. used to produce proteins, need nitrate ions from the soil to do this.

Factors affecting photosynthesis

As the light intensity increases, so does the rate of photosynthesis. This means that light intensity is a limiting factor. However, after a certain point, the light intensity no longer affects the rate of photosynthesis and so there must be another limiting factor e.g. co2 or temperature.

As the temperature increases, so does the rate of photosynthesis. This means that temperature is a limiting factor. However, after a certain point is reached, the rate of photosynthesis falls to 0 because the enzymes involved in photosynthesis have denatured.

As the concentration of co2 increases, so does the rate of photosynthesis. This means


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