Edexel Biology Paper 1 - Revision 9-1 GCSE

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Biology Paper 1 - All Topics 

- Plant Cells

Cell membrane - controlls what leaves and enters the cell

Cell Wall - gives the cell structure

Vacuole - for storage and shape

Cytoplasm - where reactions take place

Ribosomes - responsible for protein synthesis

Mitochondria - produce energy (powerhouse of the cell)

Chloroplasts - where photosynthesis takes place

Nucleus - contains DNA 

- Animal Cell

Cell membrane - controlls what leaves and enters the cell

Cytoplasm - where reactions take place

Ribosomes - responsible for protein synthesis

Mitochondria - produce energy (powerhouse of the cell)

Nucleus - contains DNA

- Bacteria Cell

Cell membrane - controlls what leaves and enters the cell

Cell Wall - gives the cell structure

Chromosome/DNA - Genetic material

Ribosomes - responsible for protein synthesis

Cytoplasm - where reactions take place

- Differentiation

All cells start off looking the same as unspecialised cells. They have the basic cell structure until they specialise (differentiate)  into what they're intended for : red blood cell, white blood cell, skin sell etc. 

Microscopes

Started off with light microscopes, which uses light to magnify objects. The greatest possible magnification using a light microscope is about x2000.

An electron microscope uses electrons to view an object. This makes it possible to magnify objects up to about x10 million. You can see objects in cells more clearly and far more detail with an electron microscope than with a light microscope.

Magnification (M) = Image size (I) / Real size (R)

- Describing Small Structures

1cm = 10⁻² meters (centimeter)

1mm = 10⁻³ meters (millimeter)

1μm = 10⁻⁶ meters (micrometer)

1nm = 10⁻⁹ meters (nanometer)

1pm = 10⁻¹² meters (picometer)

- Enzymes

Enzymes are biological catalysts that control reactions in the body. Each enzyme only works with one substrate and the activity of enzymes is affected by temperature, substrate concentration and pH. The substrate enters the active site of the enzyme and forms a product. The product molecule doesn't fit in the enzyme, causing it to be released.

At lower temperatures molecules move more slowly, so substrate molecules take longer to fit into and react in the active site. At the optimum temperature the enzyme is working at its fastest rate. Higher temperatures cause the active site to change shape, meaning it cant hold the substrate tightly causing slower reactions. At extremely high temperatures the enzyme denatures as the active site breaks up.

The optimum pH for enzymes is usually neutral. If the pH is too acidic or alkaline the enzyme denatures.

Lipase breaks down fats into fatty acids/glycerol. Made in the pancreas/small intestine and works in the small intestine.

Protese breaks down proteins into amino acids. Made in the stomach/pancreas/small intestine and works in the stomach/small intestine.

Amylase breaks down starch into sugars. Made in the salivary glands/pancreas/small intestine and works in the mouth and small intestine.

- Diffusion

Diffusion is the act of particles moving from a high concentration, down the concentration gradient to a place with a low concentration. Could happen in

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charlotteleverr

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Sorry if there are some spelling mistakes, spell check wouldn't work and it was writing them quickly :)