Biology b1, b2

• Sperm cell - bring male Dna to female Dna and fertalise
• Egg cell - fertalisied
• nerve cell - carry electrical signals
• red blood cells - carry oxygen and transport it around the body
• Muscle cells - contract quickly
• Differentiation - process by which cell changes to become specialised for its job
• Chloroplast - where photosynthesis take place. Contains chlorophyll. Pigment absorbs light
• Cell wall - made of cellulose, supports and strengthen cell wall
• Permanent vacuole - contains cell sap weak solution of salt and sugar
• Ribosomes - proteins are made
• Mitochondria- aerobic respiration takes place
• Cytoplasm- most chemical reactions take plaxe
• Nucleus - contains genetic material
• Mitosis - process where a type of cell divides into two creating two daughter cells
• Sperm cell adpation - long tail to help it swim, many mitochondria for energy
• Egg cell : contains nutrients for growth - early embroyo
• Nerve cell - long and have branched connections to form network
• Red blood cell - contains haemoglobin- bind with oxygen. Large surface area for oxygen to pass through
• Muscle cell - long- space to contract. many mitochondria to transfer the energy needed for chemical reaction
• Diffusion - movement of molecules from high concentration to low concentration
• Stomach produces hydrochloric acid to make stomach acidic for enxymes . Break down protein lowers stomach ph to 2
• Protease - stomach, pancreas , small intestine. Convert proteins into amino acids. Contains glandular tissue, produce and secrete enzymes
• Lipase - pancreas small intestine. Convert fats into fatty acids and glycerol
• Long chain of amino acids folded into specific shape and denatures if above 42
• Biological catalysts speed up chemical reactions
• Chemical reactions - occur in cytoplasm
• Liver make bile to neutralise the acid so enzymes in small intestine can work
• Root hair cells - greatly increase the surface area available for water to move into the cell. Have many mitochondria - transfer the energy needed for active transport of mineral ions into root hair cells long projection speeds up the absorption of water and

  mineral ions by increasing the surface area of the cell
• Photosynthetic cell - large permanent vacuole that keep cell rigid, have chloroplasts contain chlorophyll that trap light needed for photosynthesis
• Xylem cells - transport water and mineral ions from roots to the stem and leaves. They also support the plant. They are living when first formed and then chemical called lignin builds up in spirals in cell walls
• Phloem cell - the cell walls between phloem cells break down to form sieve plates. They lose a lot of their structure but are kept alive by their companion cell
• Examples of diffusion - diffusion of oxygen and glucose into cells of the body from bloodstream for respiration. Diffusion of carbon dioxide actively photosynthesising plant cells
• Two solutions with same concentration - isotonic

  Solution that is less concentrated - hypotonic

  Solution that is more dilute - hypertonic
• Adult stem cell - differentiate to form certain type of cell . Advantages - fewer ethical issues - adults can consent to have their stem cell removed and used. Disadvantages - requires a donor , meaning long wait
• Water is lost through the stomata by evaporation. This pulls water up from the roots through the xylem and is called transpiration.
• The movement of dissolved sugars from the leaves to the rest of the plant through the phloem.
• How are the lungs adapted for efficient

  gas exchange?

  alveoli – large surface area

  • moist membranes – increases rate of diffusion

  • one-cell-thick membranes – short diffusion pathway

  • good blood supply – maintains a steep concentration

  gradient
• How are fish gills adapted for efficient

  gas exchange?

  large surface area for gases to diffuse across

  • thin layer of cells – short diffusion pathway

  • good blood supply – maintains a steep concentration

  gradient
• Red blood cells are specialised animal cells. Compare the structure of a red blood cell with structure of plant cell

  Red blood contains haemoglobin, plant cells do not

  Plant cells have a nucleus, red blood cell doesn't

  Plant cell have a cell wall, red blood cell doesn't

  Red blood cell do not contain chlorophyll

  Red blood cell are shaped like a biconcave disc
• Osmosis is the movement of water from a dilute to more concentrated solution across a partially permeable membrane