What are some examples of waste products in plants
Oxygen
Carbon dioxide
Water
Other unwanted chemical substances
During the day (when there is sufficient light) -
Rate of photosynthesis is higher than rate of respiration
More oxygen is produced than used in respiration
Less carbon dioxide is produced than used in photosynthesis
NET EFFECT - Oxygen is in excess and is a waste product
During the night (when there is insufficient light) -
There is no photosynthesis, only respiration
Oxygen is used in respiration and carbon dioxide is produced
No photosynthesis means no carbon dioxide being used
NET EFFECT - Carbon dioxide is in excess and is a waste product
Where does the gas in excess come out from
They diffuse out of the plant via the leaf organ and the gases then exit through the stomata
Where are chemical waste materials stored in a plant
In the dying tissues of a plant
What are some examples of metabolic waste in humans
Carbon dioxide and water (from aerobic respiration)
Urea (produced by breakdown of excess proteins, amino acids, in liver)
Other substances in excess (like drugs)
What are the dangers of waste products in humans
Toxicity
Osmotic effect
Using up necessary storage
Toxicity
Waste products can have toxic effects if able to reach high concentrations
Carbon dioxide can dissolve in water to produce an acidic solution which lowers the pH of cells.
This can reduce the activity of enzymes in body which are essential for controlling the rate of metabolic reactions
Osmotic effect
Body fluids can become more concentrated due to higher amounts of waste products
Concentrated body fluids can cause water to move out of cells, changing their water potential possibly preventing them from carrying out essential reactions
What are the organs used in excretion
Skin
Lungs
Kidneys
Liver
Skin
Excretes excess mineral ions (sodium and water) + some urea
Does this via sweating
Lungs
Excretion of carbon dioxide and water
Does this via exhalation
Water in the form of vapour
Kidneys
Excretion of urea, water and excess salts
Does this via urine
Urea comes from breakdown of excess amino acids in the liver
Liver
Produces urea from amino acids
2 most important features of the kidney
The regulation of the water content of the blood
Excreting the toxic waste products of metabolism
Waste substances that need to be removed from the blood
Urea
Creatinine
Excess hormones
Excess water
Ammonia
Uric acid
Excess salts/ions
Osmoregulation
Process of maintaining water and salt concentrations across the membranes within the body
(Example of homeostasis within humans)
What does too much water in the blood do
Cells swelling
Can lead to cell lysis (bursting)
What does too little water in the body do
Cells loose water by osmosis (become dehydrated)
Can result in cell death
Hypertonic solution
When red blood cells have a higher water potential than solution
Net movement of water out of cells
Cells become shrivelled
Isotonic solution
Water potential equal between solution and red blood cells
No net movement of water
Normal cells
Hypotonic solution
Red blood cells have a lower water potential than solution
Net movement of water into the cells
Cells swell and may lyse (burst)
2 key functions of the urinary system
Filter waste products from the blood
Controls water levels of blood
How are the kidneys joined to the bladder
With 2 tubes called ureters
What does the urethra do
Carries urine to outside the body
Each kidney is also connected to:
The renal artery - comes from the aorta and delivers oxygenated blood to the kidney
The renal vein - delivers the deoxygenated blood from the kidney to the vena cava
What are the 3 regions of the kidneys
Cortex - outermost region
Medulla - inner section kidney
Renalpelvis - Tube linking kidney to ureter
What sections do nephrons contain
The Bowman's capsule
Proximal convoluted tube
Loop of Henle
Distal convoluted tubule
Collecting duct
What is the process of reabsorption of the useful substances in the blood
Ultrafiltration
Selective reabsorption of glucose
Selective reabsorption of water and salts
Arterioles branch off to each nephron, where they form a bundle of capillaries (the glomerulus) inside the Bowmans capsule
The capillaries get narrower as they get further into the the glomerulus which increases the blood pressure
Eventually this causes smaller molecules present in the blood to be forced out of the capillaries and into the Bowmans capsule, where the glomerular filtrate is formed
What substances are present in the glomerular filtrate
Glucose
Water
Urea
Salts
Protiens and red blood cells are too large to be forced out during ultrafiltration so therefore are not present in kidney filtrate
How is glucose reabsorbed at the proximal convoluted tube
Active transport
Nephron has many mitochondria to help with this
These mitochondria provide the energy for the active transport