biology 3
- Created by: Georgia Chater
- Created on: 05-05-13 15:54
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- Biology
- Osmosis
- type of diffusion
- movement of water from DILUTE (aq) to CONCENTRATED (aq)
- through partially permeable membrane
- small molecules only
- demonstrated by visking tubing
- water molecules move about, hit the walls, and go through the holes.
- water flows to the more concentrated side
- Animal cells in:
- more concentrated (aq) than cytoplasm, water leaves and cell shrinks
- less concentrated (aq) than cytoplasm, water enters and cell bursts
- Plant cells in:
- more concentrated (aq) than cytoplasm, water leaves cell and membrane moves away from cell wall
- less concentrated (aq) than cytoplasm, water enters and membrane pushes against cell wall
- type of diffusion
- Active Transport
- requires energy from cell respiration
- comes from mitochondria-breaks down glucose & combines them with oxygen to release energy
- molecules move against concentration gradient
- dilute to concentrated
- used by root cells to absorb minerals
- oxygen from airs spaces in the soil
- proteins in membrane transport molecules from surroundings into cells
- requires energy from cell respiration
- Exchange surfaces
- take substances from surroundings & remove others
- lungs- alveoli absorb oxygen and release CO2
- s.intestines- villi absorb nutrients from food
- proteins for active transport absorb nutrients against concentration gradient
- kidneys- nephrons remove urea from blood
- for efficient exchange, they have:
- large surface area
- small distance for diffusion
- movement to maintain concentration gradient
- Gas exchange
- oxygen diffuses in to blood, CO2 diffuses out.
- happens in alveoli in the lungs
- air to reach alveoli passes through trachea, bronchi & bronchioles
- happens in alveoli in the lungs
- alveoli & capillaries only 1 cell thick- short distance for diffusion
- movement of blood & ventilation maintains the c-gradient for diffusion
- singe celled organisms have a large s.a:volume don't need a ventilation system.
- multicellular organisms have small s.a:volume so need specially adapted gas exchange surfaces
- oxygen diffuses in to blood, CO2 diffuses out.
- Breathing
- inspired air: breathed in
- expired air: breathed out
- air pushed in & out by muscles in-between ribs & diaphragm
- Blood
- platelets: blood clotting
- plasma: pale, yellow liquid, carries dissolved nutrients and waste
- red blood cells contain haemoglobin-carries oxygen
- haemoglobin oxygen= oxyhaemoglobin
- when blood passes through:
- lungs: CO2 diffuses out, oxygen diffuses in
- s.intestines: absorbs nutrients
- kidneys: urea diffuses out
- Transport in plants
- xylem: water from roots to leave & stem
- loss of water reduces xylem pressure
- made up of dead cells & is hollow
- phloem: dissolved sugars from leaves to everywhere else
- water moves through plants via transpiration stream
- roots to leaves
- water enters through osmosis and leaves through xylem tissue
- photometer measures transpiration.
- hot, dry & windy places increase rate of transpiation
- xylem: water from roots to leave & stem
- Waste & water control
- CO2 is waste from respiration. removed by lungs
- urea is waste from excess amino acids in liver. removed by kideys
- kidneys filter blood, absorb everything (not ions or big molecules)
- glucose is reabsorbed leaving urea, excess water and ions.
- kidneys filter blood, absorb everything (not ions or big molecules)
- Temperature control
- thermoregulatory centre in brain controls body temperature
- temperature sensors on the skin detect if you're too cold/hot
- too hot: skin arterioles dilate, more blood to the surface & energy is lost via radiation.
- sweat evaporates and we cool down
- too cold: skin arterioles contract, blood is kept far away from the skin & muscles contract to generate heat needed for respiration
- too hot: skin arterioles dilate, more blood to the surface & energy is lost via radiation.
- Blood glucose
- pancreas detects if levels are too high and secretes insulin.
- liver cells store glucose as glycogen (insoluble)
- when levels drop pancreas releases glucogan, causing liver to break down glycogen and release to blood
- Osmosis
- phloem: dissolved sugars from leaves to everywhere else
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