Excretion and Homeostasis

Question 1

What are the waste products of plants’ metabolism?

Answer 1

Carbon dioxide and oxygen (lost through the stomata of a leaf)

Question 2

What are the organs of excretion?

Answer 2

1) the lungs (carbon dioxide)
2) the kidneys (urea)
3) the skin (salt in sweat)

Question 3

What is osmoregulation?

Answer 3

The maintenance of the water content of the blood

Question 4

What is excretion?

Answer 4

The removal of metabolic waste from the body

Question 5

What metabolic waste does the kidney remove from the body?

Answer 5

Urea (from the breakdown of protein molecules)

Question 6

Describe ultrafiltration

Answer 6

1) blood in the glomerulus is under very high pressure

2) the basement membrane acts like a filter allowing only small molecules to enter the bowman capsule

Question 7

What is the glomerular filtrate composed of?

Answer 7

1) glucose
2) water
3) urea
4) salts

Question 8

Why is glucose not found in urine?

Answer 8

1) needed for respiration
2) selectively reabsorbed at the primary convoluted tubule
3) via active transport

Question 9

What is homeostasis?

Answer 9

The maintenance of a constant internal environment

Question 10

How does ADH control the concentration of water in the blood?

Answer 10

1) the hypothalamus detects the loss of water (as concentration of blood increases)
2) it sends a signal to the pituitary glands, telling them to release more ADH
3) ADH causes the collecting duct to become more permeable to water
4) water moves back into the blood via osmosis

Question 11

What is in urine?

Answer 11

1) urea
2) water
3) salts

Question 12

Where is water reabsorbed into the blood?

Answer 12

At the loop of henlé

Question 13

How does sweating control body temperature?

Answer 13

1) sweat glands produce sweat
2) sweat evaporates on the surface of the skin
3) cools the body as heat required for evaporation is supplied by the blood

Question 14

How does hair control body temperature?

Answer 14

1) when cold erector muscles contract, pulling hair upright

2) traps an insulating layer of air next to the skin

Question 15

How does vasodilation control body temperature?

Answer 15

1) arterioles leading to the surface of the skin dilate when blood is too hot
2) increasing blood flow to the surface
3) more heat is radiated out of the body

Question 16

How does vasoconstriction control body temperature?

Answer 16

1) arterioles leading to the surface of the skin contract when blood is too cold
2) reducing blood flow to the surface
3) less heat is radiated out of the body

Question 17

what is thermoregulation?

Answer 17

the maintenance of a constant body temperature

Question 18

How are the blood vessels entering and leaving the glomerulus structures to help move substances into the bowman’s capsule?

Answer 18

1) vessel entering is wider
2) causing increases pressure
3) leading to ultrafiltration

Question 19

What do the ureters do?

Answer 19

Transport urine from the kidneys to the bladder

Question 20

What is the difference between the upper and lower sphincter muscles?

Answer 20

Lower = consciously controlled
Upper = involuntary (automatically release when bladder is full

Question 21

What is the cortex?

Answer 21

The outer layer of the kidney which is full of blood and nephrons

Question 22

What is the medulla?

Answer 22

Middle layer of the kidney which nephrons run through