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Excretion QuestionsChaiken of Biology

1. Distinguish between excretion and egestion/defecation. Why is excretion necessary for life?

EXCRETION INCLUDES BALANCING (HOMEOSTASIS) REACTION PRODUCTS, TOXINS, MOLECULES IN EXCESS AND TOO LITTLE.

EGESTION INCLUDES MOLECULES THAT ARE EXITING YOUR ANUS CHEMICALLY UNCHANGED

2. Name three excretory organs of humans. What liquids carry the urea that is excreted? Which organ of another studied organism resembles the nephron in function?

THREE EXCRETORY ORGANS: KIDNESY, LUNG, SKIN

UREA MUST BE MIXED IN WATER TO BE EXCRETED BY THE NEPHRON AND SKIN.

THE NEPHRIDIA OF THE EARTHWORM IS SIMILAR IN STRUCTURE/FUNCTION TO THE NEPHRON OF A VERTEBRATE MAMMAL KIDNEY.

3. How are the excretory wastes carbon dioxide and water produced in the body?

CARBON DIOXIDE IS AN EXCRETORY WASTE FROM RESPIRATION. IF YOU FOLLOW THE CARBONS, THEY ORIGINATED WITH ORGANIC FOOD MOLECULES. WATER IS AN EXCRETORY WASTE FROM RESPIRATION. IF YOU FOLLOW THE OXYGEN, IT ORIGINATED AS OXYGEN GAS FROM THE ATMOSPHERE.

4. What is deamination? In what forms are nitrogenous wastes excreted?

THE LIVER PERFORMS DEAMINATION. IT IS THE REMOVAL OF THE AMINO GROUP FROM AN AMINO ACID. DEPENDING ON WHO YOU ARE, WHERE YOU LIVE AND WHAT ENZYMES YOU SYNTHESIZE, THE ORGANISM MAY EXCRETE UREA, URIC ACID OR AMMONIA.

5. Why would it be disadvantageous for humans to excrete nitrogenous waste in the form of ammonia? How are fish adapted for the excretion of ammonia?

AMMONIA IS VERY TOXIC AND MUST BE IMMEDIATELY REMOVED FROM THE VACINITY OF CELLS. THIS CAN BE DONE BY IMMEDIATELY DIFFUSING IT INTO A LARGE QUANTITY OF WATER. HUMANS DO NOT HAVE ENOUGH WATER TO DILUTE THE TOXIN. FISH DIFFUSE THE AMMONIA IMMEDIATELY OUT OF THEIR GILLS. THEIR ENVIRONMENT HAS ENOUGH WATER TO DILUTE THE AMMONIA.

Completion Questions

1. Which of the following is most likely to excrete most of its nitrogenous waste as ammonia? *****a) Parameciumb) grasshopperc) pigd) the human

2. If the organism is a protozoan, the substances, which might be excreted, are a) ammoniab) carbon dioxide
******c) carbon dioxide and ammoniad) hormones

3. The major function of the contractile vacuole is
a) Removal of nitrogenous wastes*******b) homeostatic regulation of water c) digestion of foodd) removal of excess carbon dioxide

4. Which is characteristic of organisms, which excrete uric acid as their main nitrogenous waste? a) They usually live in water
*****b) They are usually land dwellers
c) They can carry on only anaerobic respiration
d) They can only do aerobic respiration

5. A certain red dye turns yellow when treated with a mild acid. If a small amount of this red dye is added to 10 cubic centimeters of water and a small aquatic animal is place in the solution, the reddish solution will turn yellow after about 20 minutes. The most reasonable explanation is that a) the animal’s body has too many acids

b) the animal is secreting acidic gastric juice into the solution *******c) carbon dioxide is diffusing out of the organism
d) oxygen is diffusing into the organism

6. The bladder of humans empties to the outside by means of the ******a) urethra b) ureter c) capillary networkd) kidney tubule

7. The fact that large numbers of mitochondria are observed in the tubule cells of nephrons suggests that this region of the nephron is involved in the process of ****a) active transportb) passive transportc) osmosisd) diffusion

8. In humans, which organ excretes water and dissolved salts? a) lungs****b) skinc) nasal cavityd) large intestine

9. The human kidneys have a function similar to the function of the contractile vacuole of protozoa in that both a) synthesize and excrete urea
b) control the excretion of all metabolic wastes
c) control the secretion of hormones
*****d) help to maintain the water balance of the organism

10. The reabsorption of glucose from the...
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