AQA Additional Science B2 Part 1

Plant and Animal Cells

• Nucleus -controls all the activities of the cell
• Cytoplasm -liquid gel where all chemical reactions take place
• Cell Membrane -controls the passage of substances in & out of the cell
• Mitochondria -Where the energy is made for the cell
• Ribosomes -where protein synthesisi takes place

Just Plants

• Cell Walls -strengthens cell and gives it support
• Chloroplasts -contains chlorophyll which absorbs light energy to make glucose
• Permanant Vacuole -a space in the cytoplasm filled with cell sap 

There are many types of animal and plant cells. As an organism matures, each cell develops into a particular type. 

The structure of the cell is linked to its function;

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    • If a cell has many mitochondria it must need a lot of energy e.g. muscle cell etc.
    • If cell has many ribosomes it is making a lot of protein, e.g. gland cells which produce enzymes
    • Cells with tails are able to move, e.g.sperm cells
    • Root Hair Cells increase surface area to absorb water and mineral ions efficiently 

• Diffusion is the spreading out of particle of gas, or of any substance in solution
• The Net Movement into or out of cells depends on the concentration of particles on each side of cell membrane
• Difference in concentration between 2 areas in concentration gradient
• larger difference = faster rate of diffusion

• Diffusion of oxegen into the cell of the body from the bloodstream as the cells are respirng (and using up oxegen
• Diffusion of Carbon Dioxide into actively photosynthesising plant cells
• Diffusion of sipmle sugars and amino acids from the gut through cell membranes

A tissue is a group of cells with similar structure and function

Animal tissues include; 

• Muscle tissue - contracts to bring about movement
• Glandular tissue - produces substances such as enzymes & hormones
• Epidermal tissue - covers parts of the body

Plant tissues include;

• Epidermal tissue - covers the plant
• Mesophyll - can photosynthesise
• Xylem & Phloem - transport substances around the plant

Organs are made of tissues

The Stomach organ is made from;

• muscular tissue to churn the stomach contents
• glandular tissue to produce digestive juices
• epithelial tissues covers the inside & outside of the stomach

The leaf, stem, and root are plant organs which contain epidermal tissues, mesophyll, xylem and phloem.

• groups of organs form organ systems to perform a particular function
• the digestive system has several organs, including the small intestine

Groups of organs work together in an organ system

Digestive system is a muscular tube which includes;

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    • glands, such as the pancreas and salivary which produce digestive juices
    • the stomach and small intestine where digestion occurs
    • liver which produces bile
    • the small intestine where aborbtion of soluble food occurs
    • the large intestine is where water is aborbed from undigested food, producing faeces