Every animal and plant is made up of cells.
Animal cells and plant cells have some of the same features, and some different.
Both cells have:
- cell membrane
Plant cells also have:
- cell wall
- permananet vacuole
Leaf cell - absorbs light energy for photosynthesis
- packed with chloroplasts
Root hair cell - Absorbs water and mineral ions from the soil
- very thin wall - a large surface area
Sperm - Fertilises an egg cell - female gamete
- head contains genetic information + enzyme that helps penetrate egg cell
- the middle is packed with mitochondria for energy
- the tail moves the sperm to the egg
Red blood cell - contains haemoglobin to carry oxygen to cells
- Thin outer membrane to let oxygen diffuse through easily
- shape increase surface area to allow more oxygen to be absorbed
- no nucleus, whole cell full of haemoglobin
Diffusion is a process that allows dissolved substances have to pass through the cell membrane to get into or out of a cell.
Diffusion occurs when particles spread.
The move from a region of high concentration to a regions of low concentration.
Diffusion happys when particles are free to move.
Particles diffuse down from a high concentration to a low concentration.
Examples of diffusion
Location Particles move From To
Gut digested food products gut cavity blood in capillary of villus
Lungs oxygen alveolar air space blood circulating around the lungs
Water can move across cell membranes because of osmosis.
For osmosis you need
- two solutions with different concentrations
- a partially permeable membrane to seperate them
Partially permeable membranes let some substances pass through them, but not others.
Osmosis is the movement of water from a LESS concentrated solution to a MORE concentrated solution through a partially permeable membrane.
Eventually the level on the more concentrated side of the membrane rises and the less concentrated side falls.
- When the concentration is the same on both sides, the movement will be the same in both directions. When this happens, the net exchange of water iz zero and there is no further change in the liquid levels.
Osmosis is important to plants.
- they gain water by osmosis through their roots
- water moves into the plant cells by osmosis - making them turgid so that they can hold the plant upright.