Chapter 13 - Excretion and Homeostasis

Question 1

Define excretion

Answer 1

the removal of waste products of metabolism

Question 2

Why might organisms remove waste?

Answer 2

because some waste may be toxic

Question 3

All cells carry out metabolic reactions…

Finish the sentence

Answer 3

which also produce waste products

Question 4

Name the 3 things respiration provides

Answer 4

1) energy
2) water
3) carbon dioxide

Question 5

What 2 products do cells use and need when doing respiration?

Answer 5

cells need the energy and use the water

Question 6

What is the waste product in respiration? Why is it a waste product?

Answer 6

carbon dioxide, it’s toxic

Question 7

Do plants excrete?

Answer 7

yes

Question 8

When do plants excrete?

Answer 8

at night when they can no longer photosynthesise

Question 9

At night, what is a plant’s only source of energy?

Answer 9

aerobic respiration

Question 10

What is urea?

Answer 10

waste product produced in the liver

Question 11

Where does urea come from?

Answer 11

the breakdown of excess amino acids and proteins

Question 12

How can urea be toxic?

Answer 12

if there is too much of it in the blood

Question 13

When the kidneys filter blood, what do they remove?

Answer 13

• urea
• excess water and ions

Question 14

When the kidneys filter blood, what do they produce?

Answer 14

urine

Question 15

Define urine

Answer 15

a solution of waste products including urea, produced by the kidneys

Question 16

Complete the diagram

Answer 16

Question 17

How is urea produced?

Answer 17

animals can’t store extra proteins or amino acids, so when you eat more than you need, they are broken down and produce urea

Question 18

Define deamination

Answer 18

the removal of the part of amino acids containing nitrogen, to form urea

Question 19

Complete the table

Answer 19

Question 20

What do the kidneys do?

Answer 20

the kidneys constantly remove urea in from the blood and excrete in as urine

Question 21

What are the 4 parts of the kidney?

Answer 21

• cortex
• medulla
• nephron
• ureter

Question 22

What is the cortex (part of the kidney)?

Answer 22

the tissue making up the outer layer

Question 23

What is the medulla (part of the kidney)?

Answer 23

the tissue making up the inner layer

Question 24

What is the nephron (part of the kidney)?

Answer 24

one of the thousands of microscopic tubes inside a kidney, where urine is made. joins up to the ureter

Question 25

Label the diagram

Answer 25

Question 26

What is the ureter (part of the kidney)?

Answer 26

The ureter is a tube that carries urine from the kidney to the bladder.

Question 28

When you have more proteins than you need, what are they broken down into?

Answer 28

carbohydrates used for energy and compounds containing nitrogen

Question 29

Where does the blood through into the kidney through?

Answer 29

renal artery

Question 30

What does the renal artery divide to form?

Answer 30

many tiny coiled capillaries called glomerulus

Question 31

What happens as blood flows through glomerulus? (in terms of molecules)

Answer 31

small molecules (like water, urea, glucose, ions) are filtered out of the blood

large molecules (like proteins and cells) stay in the blood

Question 32

How does urine form?

Answer 32

• 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

Question 33

What useful substances might nephrons reabsorb into the blood?

Answer 33

• all of the glucose
• a varying volume of water
• some ions
• some urea

Question 34

What does the amount of urea reabsorbed into the blood depend on?

Answer 34

depends on protein and water levels. this can become a problem if you don’t drink enough water or eat high protein data