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EXTENSION BIOLOGY REVISION GUIDE

1. BACTERIA, FUNGI AND VIRUSES.

All three are considered microorganisms, although viruses not by all scientists.
Bacteria:
-DNA OR RNA: Have DNA.
-REPRODUCTION: Cell divides in two (binary fission) having both divisions with their significant part of DNA, to be able to repeat the process.
-WAY TO SURVIVE: They find a source of water, food/nutrients…,oxygen and a warm environment as an animal cell, to grow and reproduce.
Fungi:
-DNA OR RNA: Have DNA
-REPRODUCTION: Spores, tiny cells, found in the sporangium are released into a good growing environment, as bread.
-WAY TO SURVIVE: Fungi are a type of plants, which have no chlorophyll and so can’t produce their own food. So, they depend on another organism, on a food source or a dead plantor animal, to live.
Viruses:
-DNA OR RNA: Have RNA.
-REPRODUCTION: They invade another living cell called a “host cell” and insert a copy of their RNA, into the nucleus. This extract of RNA, forces the host cell to produce copies of the virus. The viruses, then burst the cell and go into another.
-WAY TO SURVIVE:

2. PLANT CELLS AND ANIMAL CELLS
Diagram:3. ACTIVE TRANSPORT

-Definition: The movement of ions in and out of a cell through the cell membrane, from a region of their lower concentration to a region of their higher concentration against a concentration gradient, using energy released during repiration.

Examples:

-PLANTS: The root hair cells in plants, carry out active transport continously. They take in nitrate ions (minerals)from the soil, as the concentration of them is often higher inside the root hair cells than the concentration in the soil. So, the substances are transported against their diffusion gradient, by this process.
-HUMANS:

4. WATER POTENTIAL, OSMOSIS AND UPTAKE OF WATER IN ROOTS

5. ENZYMES

Enzymes are biological catalysts that control almost all of our metabolic reactions.

-LOCK: Isreffered to the enzyme, which has a depression called active site that fits perfectly the substrate (nutrient molecule).
-KEY: Is reffered to the substrate, as it fits the enzyme’s active site, in order to be broken down (metabolic reaction).

They are affected by the temperature and the pH.
-Enzymes work best at about human body temperature, 37ºC.
- At higher temperatures, they denature,which means that they become inactive and deform.
-At lower temperatures, their collisions with their substrate are less frequent, as they have less energy.
-Depending on their type, they work best at acidic conditions (lower pH) or at alkaline conditions (higher pH).
-So they have to be at their suitable pH, because if not they can also denature.

If they denature, the active site no longerfits the substrate and so the enzyme can´t work.

6. ENZYME USES

Enzymes can have other uses as: helping seeds to grow, being used in washing powders and making fruit juice.

-SEEDS: Enzymes are also found in plants. Seed have starch stores. When, they soak up water, the enzyme amylase breaks down the starch into maltose, because it is soluble, and so can be transported to the embryo in theseed. The embryo uses it to grow and to provide glucose molecules than can be strung together to make cellulose for the cell walls.
-WASHING POWDERS: Enzymes are able to break down colored substances from animals or plants that stain clothes, as they break the molecules into not colored ones that dissolve in water and are washed away.
Proteases break down proteins (egg stains) and lipasesbreak down fats (greasy stains).
-FRUIT JUICE: The enzyme pectinase is used to make fruit used. Pectin, is a substance which helps to stick plant cells together (fruits). Therefore, the use of pectinase, makes much easier the extraction of the juice from the fruit as the pectin is broken down.

7. FERMENTERS

Fermenters are large vessels used to grow microorganisms as bacteria. They...