b3 + b4

• cells -> tissues -> organs -> organ systems
• enzymes are biological catalysts that speed up chemical reactions
• lipase breaks lipids and fats into fatty acids
• protease breaks proteins into amino acids
• carbohydrase breaks carbohydrates into simple sugars
• mouth-> oesophagus -> stomach -> small intestine-> large intestine -> rectum
• gall bladder stores bile
• liver produces bile which neutralises stomach acid
• small intestine = absorbs food , large intestine = absorbs water
• mouth releases saliva which contains amylase
• stomach pummels food, creates protease and has stomach acid to kill bacteria
• for starch: iodine into food sample, gentle mix, if starch present it will change from orange to blue-black
• for sugars: benedicts solution into food sample, gentle heat, if sugars present it will change from blue to brick-red
• for proteins : biuret solution into food sample, gentle mix, if proteins present it will change from blue to purple/ lilac
• for lipids : sudan stain solution into food sample, shake tube to mix, if lipids present, a layer will form s the lipids separate
• to the lungs : mouth or nose / trachea / bronchus / bronchioles / alveoli
• left side of the heart pumps blood to the body
• right side of the heart pumps deoxygenated blood to the lungs
• the artery has thick muscular walls, carries blood at high pressures away from the heart
• veins have elastic walls, contain valves to prevent backflow and carries blood back to the heart at a relaxed speed
• capillaries have a 1 cell thick permeable wall for a diffusion pathway, and have a high density to allow efficient gas exchange in the body
• clockwise order of plant : waxy cuticle, palisade mesophyll tissue , xylem , phloem , stomata , guard cell , spongy mesophyll tissue, epidermal tissue
• waxy cuticle - reduces water loss
• upper epidermis - lets light through due to transparency
• palisade layer - lots of chloroplasts for photosynthesis
• spongy mesophyll - air spaces for gas exchange
• lower epidermis - gaps called stomata and guard cells let gases in and out
• xylem and phloem - deliver water and nutrients around the plant