Chapter 13 - Excretion and Homeostasis Flashcards
Define excretion
the removal of waste products of metabolism
Why might organisms remove waste?
because some waste may be toxic
All cells carry out metabolic reactions…
Finish the sentence
which also produce waste products
Name the 3 things respiration provides
1) energy
2) water
3) carbon dioxide
What 2 products do cells use and need when doing respiration?
cells need the energy and use the water
What is the waste product in respiration? Why is it a waste product?
carbon dioxide, it’s toxic
Do plants excrete?
yes
When do plants excrete?
at night when they can no longer photosynthesise
At night, what is a plant’s only source of energy?
aerobic respiration
What is urea?
waste product produced in the liver
Where does urea come from?
the breakdown of excess amino acids and proteins
How can urea be toxic?
if there is too much of it in the blood
When the kidneys filter blood, what do they remove?
- urea
- excess water and ions
When the kidneys filter blood, what do they produce?
urine
Define urine
a solution of waste products including urea, produced by the kidneys
Complete the diagram
How is urea produced?
animals can’t store extra proteins or amino acids, so when you eat more than you need, they are broken down and produce urea
Define deamination
the removal of the part of amino acids containing nitrogen, to form urea
Complete the table
What do the kidneys do?
the kidneys constantly remove urea in from the blood and excrete in as urine
What are the 4 parts of the kidney?
- cortex
- medulla
- nephron
- ureter
What is the cortex (part of the kidney)?
the tissue making up the outer layer
What is the medulla (part of the kidney)?
the tissue making up the inner layer
What is the nephron (part of the kidney)?
one of the thousands of microscopic tubes inside a kidney, where urine is made. joins up to the ureter
Label the diagram
What is the ureter (part of the kidney)?
The ureter is a tube that carries urine from the kidney to the bladder.
When you have more proteins than you need, what are they broken down into?
carbohydrates used for energy and compounds containing nitrogen
Where does the blood through into the kidney through?
renal artery
What does the renal artery divide to form?
many tiny coiled capillaries called glomerulus
What happens as blood flows through glomerulus? (in terms of molecules)
small molecules (like water, urea, glucose, ions) are filtered out of the blood
large molecules (like proteins and cells) stay in the blood
How does urine form?
- blood flows into the kidney through renal artery
- the artery divides to form glomerulus
- as blood flows through glomerulus, small molecules get filtered out of the blood, and large molecules remain in the blood
- all of the filtrate substances then move into the nephron
- nephrons re-absorb any useful substances back into the blood
What useful substances might nephrons reabsorb into the blood?
- all of the glucose
- a varying volume of water
- some ions
- some urea
What does the amount of urea reabsorbed into the blood depend on?
depends on protein and water levels. this can become a problem if you don’t drink enough water or eat high protein data
