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Define the term metabolism.
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Define the term metabolism.
The term metabolism refers to the chemical reactions that occur inside living cells.
Give two examples of metabolic waste products produced by plants.
Waste products produced by plants include:
Oxygen
Carbon dioxide
Water/water vapour
Which metabolic process in plants produces carbon dioxide as a waste product?
The process in plant cells that produces carbon dioxide as a waste product is respiration.
True or False?
The process of photosynthesis produces water vapour as a waste product in plants.
False.
Photosynthesis produces oxygen as a waste product. Water is produced as a waste product of respiration.
How does light intensity affect waste product accumulation in plants?
The intensity of light determines which gas accumulates as a waste product. At high light intensity more photosynthesis occurs so oxygen accumulates, while at low light intensity more respiration occurs so carbon dioxide accumulates.
What is likely to be the main waste product in plants during daylight hours?
During the day, with sufficient light for photosynthesis, oxygen is produced in excess and is the main waste product.
True or False?
Plants only respire at night and not during the day.
False.
Plants respire at night and during the day. The difference is that during the day photosynthesis occurs at a higher rate than respiration, so the waste products of photosynthesis accumulate.
Which plant structure allows gaseous waste products to exit the leaves?
Gaseous waste products exit the plant through the stomata in the leaves.
Name the process by which gaseous waste products exit the leaves of plants.
Gaseous waste products exit the leaves of plants by the process of diffusion.
True or False?
All water vapour lost from leaves is a waste product of plant metabolism.
False.
The majority of water vapour that is lost in transpiration is not a metabolic waste product, but simply water drawn up from the roots by the transpiration stream.
Define the term excretion.
Excretion is the removal from the body of the waste products of metabolism, and any substances present in excess, e.g. excess salts
Give two examples of waste products produced by human metabolic processes.
Waste products from human metabolism include:
Carbon dioxide from respiration
Water from respiration
Urea from the breakdown of excess amino acids
True or False?
Urea is produced during the breakdown of excess lipids.
False.
Urea is produced during the breakdown of excess amino acids, which come from protein digestion.
What are the main excretory organs in humans?
The main excretory organs in humans are:
Kidneys
Lungs
Skin
Which waste products of metabolism are excreted by the lungs?
The metabolic waste products excreted by the lungs are water and carbon dioxide, both produced during respiration.
True or False?
A build up of excretory products in the body fluids can cause water to move out of cells.
True.
A build up of metabolic waste can lower the water concentration of the body fluids, causing water to move out of cells by osmosis.
How are waste products excreted by the skin?
Waste products are excreted by the skin by the sweat glands when they produce sweat.
True or False?
The kidneys excrete urea, excess water and carbon dioxide.
False.
The kidneys excrete urea, excess water and excess salts. Carbon dioxide is excreted via the lungs.
What are the two main functions of the kidneys?
The main functions of the kidneys are:
Regulating the water content of the blood; this is osmoregulation
Excretion of toxic metabolic waste products and excess substances
Define the term osmoregulation.
Osmoregulation is the process of maintaining the balance of water and dissolved substances, e.g. salts, within the body fluids.
Why is osmoregulation important?
Osmoregulation is important because changes in the osmotic balance between the cells and the body fluids can lead to cells gaining or losing water by osmosis.
True or False?
When the solute concentration of body fluids becomes too high the cells of the body gain water by osmosis.
False.
A high solute concentration occurs when the water concentration is low. When water concentration of the body fluids is low water will move out of the body cells by osmosis down a water concentration gradient.
What happens if the body cells lose water by osmosis?
Losing water by osmosis causes the cells to shrink, or shrivel; this is known as crenation and can lead to inefficiency of cell activity and potentially cell death.
Name two processes that will cause an increase in the water content of the body fluids.
Two processes that will cause an increase in the water content of the body fluids are:
Aerobic respiration
Consumption of water by eating /drinking
Name the organ system responsible for the filtration of blood and the production of urine.
The organ system responsible for the filtration of blood and the production of urine is the urinary system.
True or False?
The liver is part of the urinary system.
False.
The liver has a role in many organ systems of the body, but it is not part of the urinary system, which consists of the kidneys, ureters, bladder and urethra.
What are the four main structures of the urinary system?
The four main structures of the urinary system are:
Kidneys
Ureters
Bladder
Urethra
Name the tubes that connect the kidneys to the bladder.
The tubes that connect the kidneys to the bladder are the ureters.
What is the role of the bladder in the urinary system?
The role of the bladder is to store urine that is produced by the kidneys. Urine exits the bladder via the urethra which removes it from the body.
True or False?
The ureter carries urine from the bladder to the exterior of the body.
False.
The urethra carries urine from the bladder to the exterior of the body. The ureters are a pair of tubes that connect the kidneys to the bladder.
Define the term nephron.
Nephrons are tiny tubes found in the kidney. Each kidney contains many nephrons, the role of which is to produce urine.
True or False?
Nephrons contain a Bowman's capsule, loop of Henle and renal pelvis.
False.
Nephrons contain a Bowman's capsule and loop of Henle, as well as several other structures, but do not contain a renal pelvis. The renal pelvis is the region of the kidney into which the nephrons drain.
Name the main sections that make up a kidney nephron.
The sections of a nephron include:
Bowman's capsule
Convoluted tubules (distal and proximal)
Loop of Henle
Collecting duct
Note that the glomerulus is a knot of blood vessels and is not part of the nephron itself.
Name the knot of blood vessels associated with each kidney nephron.
The knot of blood vessels associated with each kidney nephron is known as the glomerulus.
True or False?
The Bowman's capsule of each nephron surrounds a glomerulus.
True.
The Bowman's capsule directly surround the glomerulus, a ball of blood vessels from which the blood filters into the nephron.
Define the term ultrafiltration.
Ultrafiltration is the process by which molecules are forced out of the blood and into the Bowman's capsule at high pressure.
Where in the kidney does ultrafiltration occur?
Ultrafiltration occurs between the glomerulus and the Bowman's capsule.
True or False?
Ultrafiltration occurs at normal blood pressure.
False.
Ultrafiltration occurs at high blood pressure. The narrowing capillaries of the glomerulus increase the blood pressure, forcing small molecules into the filtrate.
What determines whether a molecule enters the filtrate or remains in the blood during ultrafiltration?
Whether a molecule enters the filtrate or remains in the blood during ultrafiltration depends on its size; small molecules are filtered and large molecules remain in the blood.
Name the substances that are forced out of the capillaries during ultrafiltration.
Substances that are forced out of the capillaries during ultrafiltration are:
Glucose
Water
Urea
Salts
These molecules form the glomerular filtrate.
Define the term glomerular filtrate.
Glomerular filtrate is the liquid that enters the Bowman's capsule during ultrafiltration. It contains water, glucose, salts and urea.
True or False?
Glucose enters the glomerular filtrate due to active transport.
False.
Glucose enters the glomerular filtrate due to high blood pressure during ultrafiltration. Active transport is not involved in this process.
Define the term reabsorbed in the context of the kidneys.
Reabsorption occurs when substances are taken back up into the blood after having been filtered by the kidneys.
True or False?
Proteins do not enter the filtrate during ultrafiltration.
True.
Only small molecules are forced into the filtrate during ultrafiltration. Proteins are too large and remain in the blood.
From which parts of the nephron does water reabsorption take place?
Water reabsorption in the nephron occurs in the following locations:
Loop of Henle
Collecting duct
True or False?
The volume of water reabsorbed by the kidneys is determined by blood water potential.
True.
Existing blood water potential determines the volume of water reabsorbed by the kidneys:
High blood water potential will cause less water to be reabsorbed
Low blood water potential will cause more water to be reabsorbed
How do sodium ions contribute to water reabsorption in the kidneys?
Water reabsorption in the kidneys occurs as follows:
Salts, e.g. sodium ions, move out of the loop of Henle, primarily by active transport
This lowers the water concentration of the surrounding tissue
Water moves out of the loop of Henle and the collecting duct by osmosis
True or False?
A high salt diet can result in an increase in sodium reabsorption in the kidneys. This can lead to an increase in blood volume.
True.
An increase in salt reabsorption lowers the water concentration of the tissues around the nephron more than usual. This will result in a steeper water concentration gradient and more water will be reabsorbed by osmosis. This water will increase the blood volume and can lead to high blood pressure.
From which part of the nephron is glucose reabsorbed?
Glucose is reabsorbed from the proximal convoluted tubule.
Define the term proximal convoluted tubule.
The proximal convoluted tubule is the first part of the kidney nephron after the Bowman's capsule.
By what process is glucose reabsorbed in the kidneys?
Glucose is reabsorbed on the kidneys by active transport.
What cellular feature allows the cells that line the proximal convoluted tubule to reabsorb glucose?
The cells that line the proximal convoluted tubule have many mitochondria to release energy for the active transport of glucose.
True or False?
Glucose can be reabsorbed anywhere in the kidney nephron.
False.
Glucose reabsorption can only occur in the proximal convoluted tubule. This is because glucose transporters are located in this part of the nephron.
True or False?
Glucose in the urine can be a sign that blood glucose levels are higher than normal.
True.
When blood glucose levels are high the nephron is unable to reabsorb all of the glucose from the filtrate. The glucose is excreted in the urine and can be detected by a glucose test.
What happens to any glucose that is not reabsorbed from the nephron?
Any glucose that cannot be reabsorbed remains in the filtrate and is excreted in the urine.
True or False?
Osmoregulation involves maintaining the volume of urine produced by the body.
False.
Osmoregulation involves maintaining the balance of water and solutes in the blood. This is achieved by changing the volume of urine produced.
Name the hormone that controls water reabsorption in the kidneys.
The hormone ADH (antidiuretic hormone) controls water reabsorption in the kidneys.
Where in the body is the hormone ADH produced?
ADH is produced by the pituitary gland in the brain.
What effect does ADH have on the kidney tubules?
ADH affects the permeability of the collecting ducts to water:
An increase in ADH results in increased permeability
A decrease in ADH results in decreased permeability
True or False?
When blood water levels are too high there is a decrease in ADH production and a decrease in water reabsorption by the kidneys.
True.
If blood water content is too high less ADH is released, leading to less water reabsorption by the collecting duct; this results in production of dilute urine.
What happens to ADH and water reabsorption when blood water content decreases below normal levels?
If blood water content is too low, more ADH is released, leading to more water reabsorption by the collecting ducts; this results in production of concentrated urine.
True or False?
Drinking lots of water on a cool day will lead to a decrease in ADH secretion.
True.
Drinking lots of water and not sweating on a cool day will result in an increased blood water content. The brain will release less ADH, resulting in decreased water reabsorption and production of dilute urine.
True or False?
High ADH levels result in more dilute urine.
False.
High ADH levels cause more water reabsorption; this leads to production of concentrated urine.
What are the three main components of urine?
The three main components of urine are:
Urea
Water
Ions
What is urea?
Urea is a waste product formed during the breakdown of excess amino acids from protein digestion.
How does increasing water intake affect urine concentration?
Increased water intake results in urine that is less concentrated as there is a higher concentration of water in relation to urea and ions.
True or False?
Urine that contains glucose or proteins can indicate health problems.
True.
Glucose and protein are not components that we expect to find in urine (the main components are water, ions and urea), so their presence can indicate a health condition, e.g. glucose can indicate problems with blood glucose control and protein can indicate kidney damage.