Excretion And Osmoregulation

Question 1

Define what is homeostasis?

Answer 1

Is the means to maintain a stable internal environment/condition.

Question 2

What are some processes practiced by organisms to maintain homeostasis? (name 3)

Answer 2

1.Regulation of blood pH.
2. Regulation of blood sugar level.
3. Regulation of excess water and ions by the kidney and liver in vertebrates.

Question 3

Differentiate between excretion and egestion.

Answer 3

Excretion is the process of removing nitrogenous/metabolic waste products from the body whereas egestion is the removal of undigested food from the body via the alimentary canal.

Question 4

What are the two major metabolic wastes?

Answer 4

Carbon dioxide from respiration and nitrogenous wastes from deamination of amino acids.

Question 5

What is osmoregulation?

Answer 5

Is the process of maintaining the solute concentrations constant in the fluid in and around cells to avoid it from becoming excessively turgid or flaccid.

Question 6

What are some adaptations of plants for water conservation?

Answer 6

*Waxy cuticle- prevents water evaporation.
*Adjustment of leaf arrangements- they can adjust the angle of their leaves to reduce the amount of the leaf surface exposed to sunlight.
*Succulence- plants storing water in stems and fleshy leaves e.g. aloe vera and cactus.
*CAM plants- capture co2 at night and keep their stomata’s closed in the day time, while continuing to photosynthesize.

Question 7

Describe how plants carry out excretion?

Answer 7

During the day, the excess oxygen gas produced by photosynthesis is released from the stomata. At night, carbon dioxide is not used up as fast as it is produced and is released as a waste product.

Question 8

Explain how plants excrete waste through abscission.

Answer 8

The waste is accumulated in the vacuoles of the aging leaf cells which eventually die and fall off, removing waste in the process.

Question 9

Name 3 excretory products retained from the bark of the trees.

Answer 9

1. Resins
2. Gums
3. Latex

Question 10

Explain how osmoregulation in paramecium occurs.

Answer 10

Since the concentration of solute is higher inside the cytoplasm, water constantly moves into the paramecium. To maintain solute balance, paramecium has special organelles called contractile vacuoles that actively pump excess water out of the cell. The pumping of water is done against the concentration which requires energy hence the contractile vacuoles are surrounded by mitochondria.

Question 11

Why is osmoregulation a problem for aquatic animals?

Answer 11

Due to osmosis. Water moves into freshwater animals and out of saltwater animals.

Question 12

What results into nitrogenous wastes?

Answer 12

Breakdown of excess amino acids.

Question 13

What are the three types of nitrogen containing wastes?

Answer 13

1. Ammonia-
2. Urea
3. Uric acid

Question 14

Comment on the waste ammonia.

Answer 14

It is highly poisonous and toxic. The original product of deamination. It must be diluted with plenty of water. Excreted by fish and tadpoles.

Question 15

Comment on the waste Urea

Answer 15

It is made from ammonia but not as toxic as ammonia. Excreted by terrestrial mammals.

Question 16

Comment on the waste Uric acid

Answer 16

insoluble nitrogen waste crystals. Not toxic. Excreted by insects and reptiles.

Question 17

Explain how excretion takes place in an earthworm?

Answer 17

Carbon dioxide is diffused through their skin whereas nitrogenous waste is filtered by a pair of simple filtering tubes in each segment called nephridia, that lie on the side of the gut.

Question 18

Explain how excretion takes place in an insect?

Answer 18

They use the malpighian tubules that float in the open cavity, it absorbs nitrogenous wastes from the blood and converts it to uric acid.

Question 19

Describe adaptations of insects to conserve water.

Answer 19

1. They excrete solid uric crystals instead or urea that needs to be diluted by water.
2. Partially close their spiracles when not in use.
3. the hind gut absorbs water from the faeces
4. Wax covers the exoskeleton that which reduces water evaporation from their body.

Question 20

How is the form of waste ammonia, efficient for fish?

Answer 20

Fish have plenty of water around them that dilute the ammonia they excrete, hence they save energy by would be needed to convert ammonia to urea.

Question 21

Explain how freshwater fish overcome osmotic problems.

Answer 21

The concentration of solute in cells is higher inside the cytoplasm than the outside. To maintain the water balance, fish constantly excrete large amounts of diluted urine. Fish uses special cells in their gills to absorb the lost salt from their surrounding.

Question 22

Explain how saltwater fish overcome osmotic problems.

Answer 22

The saltwater has higher concentration of solute compared to the fluid inside the fish cells, therefore water is constantly lost by osmosis. To overcome this, fish constantly drink saltwater and then excrete the salt through their special cells present in their gills.

Question 23

Why do amphibians live in moist area?

Answer 23

Their skin do not have protective coverings because they use if for gas exchange. They lack adaptations for water conservation hence that’s why they live in moist areas.

Question 24

What form of waste do amphibians excrete?

Answer 24

Urea, which requires water for dilution.

Question 25

What do scales in a reptile do?

Answer 25

Prevent water evaporation from the skin.

Question 26

Describe how reptiles conserve water.

Answer 26

1.They carry out gas exchange through their lungs which is inside the body.
2. They excrete uric acid which conserves water.

Question 27

Give 3 advantages of excreting uric acids.

Answer 27

1. Reduces water loss since it does not require dilution.
2. Uric acid is lighter compared to liquid urine, thus it aids in flights as it does not add on extra weight.
3. Embryos developing in an egg do not poison themselves with their own wastes since uric acid is harmless compared to ammonia and urea.

Question 28

State 3 ways in which birds prevent dehydration.

Answer 28

1. They have feathers covering their body.
2. They have scales on their legs.
3. They conduct gas exchange through lungs which are kept moist inside their body.

Question 29

What form of wastes do mammals excrete?

Answer 29

They excrete urea which is diluted in water.

Question 30

Why are mammals required to drink water regularly?

Answer 30

Because they lose water through urine, by evaporation and by exhalation.

Question 31

Why are humans required to drink plenty of water?

Answer 31

Because we lack heavy fur to prevent evaporation from our skin.

Question 32

Why do some mammals like camels, well adapted to water conservation?

Answer 32

Because they survive only on water derived from respiration and food.

Question 33

Where in the kidney does osmoregulation occur?

Answer 33

At the loop of Henle.

Question 34

What happens at the loop of Henle, in the kidney?

Answer 34

Most of the body fluids and essential nutrients are reabsorbed.

Question 35

What happens in the large intestine?

Answer 35

Reabsorption of water from the undigested food.

Question 36

Which hormone is responsible for maintaining osmoregulation?

Answer 36

ADH, Anti- Diuretic hormones.

Question 37

Why is there a need for water levels in blood to be constant?

Answer 37

To avoid cell damage.

Question 38

Explain what happens in your blood when you get dehydrated.

Answer 38

The pituitary glands release the ADH hormones into the bloodstream. It travels in the blood to the kidneys where it affects the tubules so more water is reabsorbed in your blood. This leads to lesser volumes of more concentrated urine to be produced.