aqa b2-cells-bbc bitesize

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  • Created by: carlssB
  • Created on: 09-05-13 20:31

cells and cell transport

  • All living things are made up of cells
  • Parts animals and plants have in common 
  • Nucleus Contains genetic material, which controls the activities of the cell Cytoplasm Most chemical processes take place here, controlled by enzymes Cell membrane Controls the movement of substances into and out of the cell Mitochondria Most energy is released by respiration here Ribosomes Protein synthesis happens here
    Extra plant cells in plants 
    Cell wall Strengthens the cell Chloroplasts Contain chlorophyll, which absorbs light energy for photosynthesis Permanent vacuole Filled with cell sap to help keep the cell turgid
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cell diagram

both cells have a membrane on the outside, and cytoplasm and a nucleus inside. In the plant only are the cell wall, vacuole, and chloroplast.  (

Generalised animal and plant cell

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bacterial cells and yeast

  • A bacterium is a single-celled organism.
  • A bacterial cell has a different structure to an animal or plant cell. It has cytoplasm, a membrane and a surrounding cell wall, but the genetic material in a bacterial cell is not in a distinct nucleus.
  • Yeast is a single-celled organism. Like bacterial cells, yeast cells have cytoplasm and a membrane surrounded by a cell wall. But unlike bacterial cells, yeast cells have a nucleus.
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specialised cells-

Cells may be specialised for a particular function. Their structure will allow them to carry this function out.

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specialised cells- leaf cells+root hair cells

cross section through a leaf cell (

Leaf cell - Absorbs light energy for photosynthesis Packed with chloroplasts. Regular shaped, closely packed cells form a continuous layer for efficient absorption of sunlight. root hair cell - has a head and tail (

Root hair cell - Absorbs water and mineral ions from the soil Long 'finger-like' process with very thin wall, which gives a large surface area.

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specialised cells-sperm cell+red blood cells

sperm cell - has a head and tail (

Sperm cell - Fertilises an egg cell - female gamete The head contains genetic information and an enzyme to help penetrate the egg cell membrane. The middle section is packed with mitochondria for energy. The tail moves the sperm to the egg. red blood cells (

Red blood cells - Contains haemoglobin to carry oxygen to the cells. Thin outer membrane to let oxygen diffuse through easily. Shape increases the surface area to allow more oxygen to be absorbed efficiently. No nucleus, so the whole cell is full of haemoglobin.

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diffusion of cells

Dissolved substances have to pass through the cell membrane to get into or out of a cell. Diffusion is one of the processes that allows this to happen.

Diffusion occurs when particles spread. They move from a region where they are in high concentration to a region where they are in low concentration. Diffusion happens when the particles are free to move. This is true in gases and for particles dissolved in solutions. for example.

Gut Digested food products Gut cavity Blood in capillary of villus

Remember, particles continue to move from a high to a low concentration while there is a concentration gradient.

In the lungs, the blood will continue to take in oxygen from the alveolar air spaces provided the concentration of oxygen there is greater than in the blood. Oxygen diffuses across the alveolar walls into the blood, and the circulation takes the oxygen-rich blood away.

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