Biology AQA mock revision

• Eukaryote: Complex and include all animal and plant cells.
• Prokaryote: Smaller and simpler than eukaryote. (e.g. bacteria)
• Eukaryote has: A cell membrane, cytoplasm, genetic material that is enclosed in the nucleus.
• Prokaryote has: cytoplasm, cell membrane, cell wall, NO nucleus, single cell loop of DNA, plasmids. (small ring of DNA)
• Animal cell contains: nucleus, mitochondria, cytoplasm, cell membrane, ribosomes.
• Plant cell contains: cell wall, chloroplast, pernament vacuole. (filled with cell sap.)
• Cells specialised to carry out a particular function: Sperm cells, nerve cells, root hair cells, xylem and phloem cells.
• An electron microscope has much higher magnification and resolving power than a light microscope. This means it can be used to study cells in greater detail.
• Magnification = image size / real size.
• cell cycle, mitosis:

  1. duplicates its DNA.

  2. DNA is copied and forms 'X' shaped chromosomes.

  3. chromosomes migrate to opposite ends of the cell.

  4. The cell divides into two.

  (Each daughter cell has the same number of chromosomes as the original cell.)
• Stem cell is an undifferenciated cell of an organism which changes to become specialised.
• Stem cells from embyro can be cloned and made to differenciante into most different type of human cells.
• stem cells from adult bone marrow can form red blood cells .
• meristen tissue in plants can differenciate into any type of plant cell.
• treatment with stem cells can help diabetes and paralysis.
• Duffisuion: gas particles spreading from an area of high concentration to an area of low concentration.
• Factors affecting diffusion: temp, surface area, concentration.
• Osmosis: diffusion of water molecules from a dilute solution to a more concentrated solution from a partially permable membrane.
• Active transport: movement of particles againast a concentration gradient
• Cells: a group of tissues working together.
• tissues: a group of cells working together.
• organs: a group of tissues working together.
• organ system: a group of organs working together.
• Enzymes catalyse specific reactions in living organisms due to the shape of their active site.
• Enzymes denature at high temp.
• Amylase is a starch emzyme.
• Amylase breaks down starch.
• Digestive enzymes convert food into smaller soluable molecules that can be absored into the blood stream.
• Carbohydrase breaks down carbs into simple sugar.
• protease breaks down proteins into animo acids.
• lipase breaks down lipids to fatty acids and glyecerol.
• Bile is made in the liver and stored in the gall bladder.
• products of digestion are used to build new carbs, lipids, proteins.
• Right ventricle: pumps blood to lungs where gas exchange takes place.
• Left ventricle: pumps blood around the rest of the body.
• Three types of blood vessels:

  1. Arteries.

  2. Veins.

  3. Capillaries.
• Blood is a tissue consisting of plasma in which red blood cells, white blood cells, and platelets are suspended.
• Red blood cells carry oxygen.
• White blood cells fight diseases, help immunity.
• Coronary heart disease layers of fatty material build up inside the coronary arteries, narrowing them. Resulting in a lack of oxygen for heart muscles.