Heart attacks: Blood supply is suddenly blocked from getting to the heart Coronary heart disease is the leading cause of heart attacks Blood supply is trapped by fatty substances in the coronary arteries When a plaques ruptures it causes a blood clot Can also block...
Organs: Stems Roots Leaves Tissues: Epidermal Meristem Xylem and phloem Palisade mesophyll Spongy mesophyll Leaves contain epidermal, mesophyll, xylem and phloem Phloem: translocation Made of columns of elongated cells with pores in the end walls to let cell sap...
Actual object size = Image size/magnification I=AxM Practical: 1. prepare your slide - add drop of water, specimen, iodine then coverslip 2. clip slide onto stage, select lowest power objective lens, use coarse adjustment knob, adjust focus with fine adjustment knob...
Cells are grouped into tissues and tissues are grouped into organs. Pulmonary artery – carries deoxygenated blood from heart to lungs Vena cava – brings deoxygenated blood from body to heart Aorta – carries oxygenated blood from heart to body Pulmonary vein – carries...
Veins carry deoxygenated blood from the body to the heart. They have wide passages because the blood flows slowly under low pressure. Arteries carry oxygenated blood from heart to the body. The blood has to be under high pressure, so they have strong, thick...
Mouth: How food enters the body Chewing breaks up food and mixes it with enzymes to start digestion Oesophagus: Carries food from mouth to stomach by peristalsis Peristalsis is the contraction and relaxation of muscles which pushes the food down ...
Cells differentiate to become specialized - become specialized for the job Develop different subcellular structures to be able to carry out specific functions In most animal cells, the ability to differentiate is lost at an early stage, after they become...
Flowering plants have two separate transport systems Xylem and phloem Xylem tissues transport water and mineral ions from roots to stem, leaves and flowers Phloem cells carry dissolved sugars from the leaves to the rest of the plant (including growing regions and...
Growth in plants: · Grow through all their lives · Meristems are a place where cells keep dividing · Once cells have divided, they get longer (elongate) · Meristem can specialise/differentiate Growth in animals: · Stop...
Plasma: Liquid part of the blood Carries the blood cells through the blood vessels Contains many dissolved substances such as carbon dioxide and glucose White blood cells: Larger than red blood cells Have a nucleus Some surround and destroy pathogens Some...
Osmosis – diffusion of water molecules Osmosis is the diffusion of molecules from a high to a low concentration across a partially permeable membrane. It is a special case of diffusion, the diffusion of water. Partially permeable – only lets in certain...
Substances move from an area of LOW concentration to an area of high concentration across a permeable membrane Across a concentration gradient so requires energy from mitochondria Root hair cells: Plants need mineral ions for healthy growth The concentration of...
Evaporation and diffusion of water from a plants surface (leaves) Evaporation creates a slight shortage of water so more is drawn up from the roots through the xylem cells to replace it Called transpiration stream A side-effect of how leaves are adapted for...
Growth is a permanent increase in size, length, mass and cell number. Percentile charts can help to show if your child is growing faster or slower than is normal for their age. The 50th percentile is the median. If your height is at the 50th percentile, you...
Enzymes are biological catalysts. They are found in living organisms and a catalyst changes the rate of a reaction but remains unchanged at the end of the reaction. Each enzyme is specific for its substrate, which means that it only works with that substrate. ...
Respiration is the process of releasing energy Aerobic respiration uses oxygen from the air to release energy from glucose Happens in every single cell A chemical reaction Glucose + oxygen à carbon dioxide + water + energy Diffusion: Is the movement of particles from...
− The release of energy from glucose without using oxygen. − Glucose à lactic acid + energy Advantages: · Useful for when oxygen cannot be delivered fast enough Disadvantages: · Releases less energy than aerobic respiration · ...
One villus / many villi. The large capillary network carries absorbed molcules away quickly, maintaining a steep concentration gradient for diffusion. Millions of villi means an increased surface area. The surface is formed from a single layer of cells making...
Low temperature, dim light and low carbon dioxide levels all limit the rate of photosynthesis. We can measure these by measuring the rate pondweed gives off oxygen. This can test the effect of: · Temperature, using hot and cold water baths · ...
Water and substances dissolved in the water are transported around plants in veins. Veins contains vessels called xylem and phloem. Xylem: Carries water and dissolved mineral ions up to the leaves Phloem: Sucrose is dissolved in water and carried up...
No nucleus Chromosomal DNA – carries most of the genes Some have extra circles of plasmid DNA containing additional genes Cell membrane Some have flagellum to help them move Many have a cell wall for protection, but this is made out of a different substance to plant...
Prokaryotes are single celled organisms. Eukaryotes are complex, animal and plant cells. Eukaryotes are made of eukaryotic cells. Prokaryotes: Cell wall, cell membrane, cytoplasm Small rings of DNA called plasmids No chloroplasts or mitochondria Bacterial cells...
In mitosis a cell splits to create 2 identical copies, for growth and repair. The daughter cells are diploid (2 sets of chromosomes). The chromosomes line up, get pulled apart and the cytoplasm closes around them. The chromosomes have to replace themselves first....
Embryonic stem cells: Cells in an embryo are unspecialized They divide to produce the differentiated cells in the body (differentiated = specialised) Adult stem cells: Are found in differentiated tissue, such as bone or skin They divide to repair damaged cells...
Animal cell: Cell membrane – controls what enters and leaves the cell, e.g. oxygen, carbon dioxide, glucose Nucleus – contains DNA, instructions for the cell Cytoplasm – fills the cell, reactions take place here Mitochondria – where respiration takes place, releasing...