Paper 1

• Animal and Plant cells are both eukaryotic cells as their genetic material is in a nucleus
• Bacteria cells are prokaryotic cells and their DNA is in Plasmids
• All muscle cells contain protein filaments
• Eukaryotic cells vary in size, usually between 10 and 100 micrometers
• There are two types of cells: eukaryotic cells and prokaryotic cells
• The function of nerve cells is the conduction of impulses from one neurone to another
• Axons speed up nerve impulses
• A specialised cell is a cell that has a specific function in the body
• Eukaryotic cells contain a nucleus, cell membranes, cytoplasm, mitochondria, ribosomes (plant cells also contain chloroplasts, vacuole and a cell wall)
• Cells specialise by undergoing differentiation
• Dendrites recieve signals
• axons transmit signals
• dendrites and axons allow the neuron to communicate with other nerve cells and muscles and glands
• Muscle cells are specialised for contraction and have a large nucleus and lots of mitochondria
• Nerve cells coordinate information from the brain and spinal chord to the rest of the body
• humans have trillions of cells but only 250 different types
• muscle cells contract for movement
• Phloem cells: contain subcellular structures and are living cells
• Xylem cells: hollow tubes that transport water and mineral ions from the roots to the leaves and are dead cells held up by lignin
• a hormone is a chemical made by a gland that travels in the blood
• ivf: when a couple cannot conceive naturally. a women is given FSH to make more eggs and LH to release them. the eggs are collected and mixed with sperm in a petri dish. it is left to develop an embryo and that is placed in the uterus.
• disadvantages of ivf: expensive (£1000+), 25% success rate, emotional and physically stressful, lead to multiple births, both the mother and the baby are at risk throughout pregnancy.
• small intestine absorbs nutrients
• large intestine absorbs water
• rectum stores faeces and is the final part of the digestive system
• amylase is in the saliva
• stomach contains hydrochloric acid and enzymes to break down food
• pancreas makes enzymes that help the small intestine digest food
• small intestine is where nutrients from food are absorbed into the blood
• large intestine is where water is reabsorbed into the body
• liver makes bile to help the small intestine emulsify fat
• oesophagus is the tube that delivers food from the mouth to the stomach
• enzymes are made of protein
• amylase: breaks down starch into sugar and is found in the mouth and the small intestine
• lipase: breaks down lipids into fatty acids and glycerol and is found in the small intestine
• protease: breaks down proteins into amino acids and is found in the stomach and the small intestine
• bile is not an enzyme but breaks down lipids into small pieces so lipase can work. its made in the liver and works in the small intestine
• hydrochloric acid does not break food down and is in the stomach to help enzymes work better and kill bacteria
• pacemaker helps the heart beat at a regular pattern
• coronary artery provides blood flow to the heart muscle