• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12

Biology revision points and complete definetions of all questions and biological problems

Extracts from this document...


Biology revision points and complete definetions of all questions and biological problems Characteristics of living organisms. Living things are called Organisms. Living organisms have Seven characteristics that make them different from non-living things: IT is much easier to learn them in this abbreviation: MRS GREN. Movement: This is very easy to see in most animals, but it is not easy to see in plants way in movement. Movement may occur when the organism needs some kind of source to live better may be for food and hunting for shade and even to hide from predators. Most plants are rooted to the ground so the whole plant cannot move. But parts of plants may slowly perhaps only the contents of their cells move. So that you only see the movement under a microscope. Respiration: This means that they break down food inside their cells, sometimes by combining it with oxygen. This releases energy from the food, and the organisms can use this energy to carry out the rest of the seven characters. Sensitivity: Living organisms are sensitive towards their surroundings. They can sense changes in their surroundings and respond to this change. This is sometimes also called Irritability. The changes they sense are of many types, such as temperature, light intensity, sound, day length and the presence of chemicals and the amazing sense of danger when predators are around. ...read more.


Remember: Arachnids are segmented in to two parts cephalothoraxes and the abdomen cephalothoraxes just simply mean that their head is attached to their thorax and they have 8 legs also they have no antennas and they have eyes a good example is a spider. Remember: Crustaceans are also cephalothoraxes and have jointed legs they have a hard shell covering them called a ( carapace) covering their segmented body and they have a calcified skeleton made out of calcium salts and they have above 8 and less then 20 as a range for the number of legs they own. They have 2 pairs of antennas Remember: MYRA PODS are highly segmented they have one pair of antennas and they are leg jointed their exoskeleton is made of chitin and they have a head and they also have eyes the range of legs they have is above ten less than twenty good examples of Myra pods are centipedes and millipedes. Fungi :In some ways fungi are a little like plants, They grow rooted to the spot and do not move around. However, fungi do not photosynthesis, and do not have chlorophyll. Instead, they feed on other living or dead organisms. They do this by producing enzymes which seep out from the fungus in to what ever it is growing on. The enzymes digest this food, which is then soaked up into the fungus's body. ...read more.


Some of them go right through the cells making up the well of the alveolus and the wall of the blood capillary, right through the blood plasma, and through the cells surface membrane of a red blood cell. There are usually a lot of oxygen molecules in the air in the alveoli, and not many in side the red blood cells, so the net movement of oxygen molecules is from the alveoli into the blood (although some will, of course, go the other way as well!). The oxygen moves down a concentration gradient, by diffusion. Diffusion of gas molecules takes place in plants too. In day light, the palisade and spongy mesophyll cells in a plant leaf photosynthesis. They use carbon dioxide and water to make sugars. These sugars may be turned into starch in the leaf. Where does the carbon dioxide come from, and how does it get to these cells? Air contains carbon dioxide-though not very much. About 0.04% of the air is carbon dioxide. These carbon dioxide molecules bump randomly around. Some of them will go through the stomata on the underside of a leaf, into air spaces in between the leaf cells, into a mesophyll cell and into a chloroplast can be made in to sugar. This keeps the concentration of carbon dioxide molecules inside the chloroplast much lower than the concentration in the air out side the leaf, so there is a concentration gradient from the air to the chloroplast. The net movement of the carbon dioxide molecules is down this concentration gradient. . ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. A Level Biology revision notes

    molecules for holding cells to extracellular matrix Vitamins * Often interact with enzymes to speed up metabolic reactions * Most are essential (must be absorbed from food) * Only vitamin D (skin) and vitamin K (gut bacteria) are non-essential (produced by body)

  2. My presentation on the material wood.

    > The three major elements of wood are carbon, oxygen, and hydrogen. They are combined in complex molecules that are then joined into polymers. These polymers provide the structural integrity of wood. In addition, wood contains small quantities of other organic and inorganic compounds.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work