B1 Flashcards
Cells
Cab be either prokaryotic or eukaryotic
Eukariotic cells
Include all animal and plant cells. Contains nucleus
Prokaryotic cells
Smaller amd simpler compared to eukaryotic eg. Bacteria no nucleus
Nucleus
Contains genetic material that controls the activities of the cell
Cytoplasm
Gel-like substance where most of the chemical reactions happen. It contains enzymes that control these chemical reaction
Cell membrane
Holds the cell together and controls what goes in and out
Ribosomes
Site of protein synthesis (where proteins are made)
Animal cells
Nucleus, cytoplasm, cell membrane, mitochondria and ribosomes
Plant cells
Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, cell wall, permanent vacuole, chloroplasts
Rigid cell wall
Made of cellulose. It supports the cell and strengthens it
Permanent vacuole
Contains cell sap
Chlorplasts
Where photosynthesis occurs, which makes food for plants. Contain chlorophyll which absorbs light needed for photosynthesis
Light microscopes
Use light and lenses to form an image of the specimen
Electron microscopes
Uses electrons instead of light to from an image. Higher magnification than light microscopes
Magnification formula
Magnification=image size/real size
Units
1km=1000m,1m=100cm,1cm=10mm,1mm=1000micrometres,1micrometre=1000nanometres
Preparing slide microscope
Clean slide, cut onion and seperate layer using tweezers, place the tissues into water on slide, add drop of iodine to stain, place cover on slip carefully lowering so no air bubbles
Using microscope
Clip in slode, select lowest magnification lense, use coarse adjustment knob, look down eyepiece adjusting knob until rough image, adjust focus eith focus adjustment knob until get clear image of slide, if need swap to higher magnification lense
Cell differentiation
When a cell changes to become specialised for certain jon
Sperm cells- reproduction
To get male DNA to female DNA. Long tail and streamlined head to swin to egg and has lots of mitochondria for energy
Nerve cells-rapid signalling
Carry electrical signals from one part of body to another. Long and have branched connections at their ends to connect to other nevre cells and form a network throughout the body
Muscle cells for contraction
Function to contract quickly
Root hair cells for absorbing water and minerals
Cells on surface of plant roots which grow out into hairs that stick out into the soil giving plant larger surface area for absorbing water and mineral ions from soil
Phloem and xylem cells-transporting substances
Form phloem and xylem tubes
Phloem tubes
Transport food
Xylem tube
Transports water and mineral ions
Diffusion
Spreading out of particles form an area of higher concentration to area of low concentration
Conecntration gradient
Difference in concentration
What speeds updiffusion rate
Bigger concentration gradient, higher temperature as particles will have more energy, larger surface area of the membrane
Osmosis
The movements of water molecules across a parially permeable membrane from a region of higher water concentration to a region of lower water concentration
concentrated
Low concentration of water
Dillute
High concentration of water
Active transport
Substances absorbed against concentration gradient from lower to higher concentration
Active transport in plants
Allow the plant to absorb minerals from very dillute solution against concentration gradient so they can grow.
What is need for active transport
Energy from respiration
Active transport in humans
When there is lower concentration of nutrients in gut than blood diffusion wont be able to transport the nutrients to the blood
Surface area to volume ratio
As an organism gets bigger the surface area to volume ratio decreases increasing the difficulty to exchange material quick enough
Exchnage surfaces are adapted to maxmium effectiveness
Large surface area so lots of substance can diffuse at once, thin membrane so short distance to diffuse
Exchange surfaces in animals
Lots of blood vessels to get stuff into and out of blood quickly, often ventilated air moves in and out
Mitochondira
Mitochondria the site of aerobic respiration, so they release energy for the cell
