B6: Excretion and Osmoregulation

Question 1

what is excretion?

Answer 1

the process by which waste and harmful substances produced by the chemical reactions in the body are removed from the body

Question 2

difference between excretion and egestion

Answer 2

egestion is removal of undigested food as faeces while excretion is removal of waste products of metabolism from the body

Question 3

what are the waste products of plants?

Answer 3

• Oxygen - from phtosynthesis
• carbon dioxide - from respiration
• water - from respiration
• organic waste products eg tannins, alkaloids, anthocyanins, salts of organic acids such as calcium oxalate

Question 4

Mechanism of excretion in plants

Answer 4

• diffusion from the leaves- oxygen, carbon dioxide and water vapour
• some waste compounds are converted to other other substances such as oils, tannins and calcium oxalate
• organic waste is shed with the leaves.

Question 5

Products excreted by animals

Answer 5

• Bile pigments - eg bilirrubin produced by the breakdown of haemoglobin from red blod cells.
• Nitrogenous compounds produced by breakdown of proteins and aminoacids, mainly urea and ammonia.
• carbon dioxide
• water

Question 6

what are the excretory organs in plants?

Answer 6

• leaves
• Barks

Question 7

exctretory organs in humans

Answer 7

• kidney: water, urea, salts
• lungs: carbon dioxide
• liver: bile pigments such as bilirubin
• skin: water, urea, and salts

Question 8

Label parts of the excretory sytem

Answer 8

Question 9

structure and function of the kidney. label the diagram with names and functions

Answer 9

Question 10

structure of the nephron

Answer 10

Question 11

Label the nephron and state what happens at each numbered region

Answer 11

1. renal artery has greater diameter than renal vein creating high pressure in the capillaries of the glomerulus
2. the pressure forces liquid(filtrate) into the Bowmans Capsule
3. the filtrate contains useful substances and waste. large molecules and corpuscles cannot pass.
4. Convoluted tubules reabsorb the useful substances eg. glucose, salts and water
5. loop of Henle absorbs water and salts
6. blood caillaries reabsorsb useful substances and secrete toxic substances into the tubule
7. Blood has reabsorbed 80% of the filtrate
8. Urine passes to the pelvis

Question 12

Where does pressure filtration (utrafiltration occur)

Answer 12

the glomeruli

Question 13

what are the substances present in the filtrate

Answer 13

• useful substances: glucose, water, salts, hormones, vitamins, aminoacids
• waste substances: water, urea, bile salts, salts

Question 14

What is selective reabsorbtion?

Answer 14

The absorption of some of the useful components of the glomerular filtrate back into the blood as the filtrate flows through the nephrons of the kidney.

Question 15

where does selective reabsobtion take place?

Answer 15

• proximal convoluted tubules: glucose, hormones, water, vitamins, amino acids, some salts
• loop of Henle: water
• distal convoluted tubule: some salts and water

Question 16

How is urine produced in the nepron?

Answer 16

• Ultrafiltration (pressure filtration)
• Selective reabsorbtion

Question 17

How is water reabsorbed into the blood from the nephron?

Answer 17

osmosis

Question 18

How are substances such as amino acids glucose, hormones etc reabsorbed into the blood

Answer 18

diffusion and active transport

Question 19

What is the composition of urine?

Answer 19

• urea
• excess salts
• excess water

Question 20

What is homeostasis?

Answer 20

the maintenance of near normal internal conditions in the body by mechanisms of negative feedback

Question 21

feedback?

Answer 21

Negative feedback involves contolling a system, monitoring the effects of change and continually making adjustments.

Question 22

Skin structure : Identify the parts and regions of the skin

Answer 22

Question 23

What is negative feedback?

Answer 23

a type of regulation in biological systems in which the end product of a process in turn reduces the stimulus of that same process.

Question 24

4 main funtions of Homeostasis

Answer 24

• thermoregulation
• osmoregulation
• Glucose control
• Control of Carbon dioxide levels

Question 25

Describe osmoregulation

Answer 25

control of concentrations of salts and water in the blood with normal limits

Question 26

describe the regulation of carbon dioxide concentration in the blood

Answer 26

Question 27

describe the regulation of glucose concentration in the blood

Answer 27

Question 28

Describe Thermoregulation in humans

Answer 28

Question 29

label the skin

Answer 29

Question 30

what is know as the body’s thermostat?

Answer 30

The Hypothalamus

Question 31

How aspects of homeostasis does the hypothalamus regulate

Answer 31

• body’s temperature
• water and salt content of the blood(osmoregulation) by stimulating the pituitary gland to secrete ADH

Question 32

which structure detects changes in the temperature of the blood?

Answer 32

the Hypothalamus

Question 33

which structure is responsible for regulating water and salt content of the blood?

Answer 33

The hypothalamus

Question 34

which structure regulates carbon dioxide concentration in the blood?

Answer 34

medulla oblongata in the hind brain.

Question 35

what structure detects changes in the concentration of glucose in the blood?

Answer 35

Cells in the pancreas

Question 36

true or false: insuin and glucagon are hormones

Answer 36

true