Chapter 13:Excretion

Question 1

Define excretion

Answer 1

The removal from organisms of waste products of metabolism and substances in excess of requirements

Question 2

what is the main organ that excretes carbon dioxide

Answer 2

The lungs

Question 3

Explain why the removal of carbon dioxide from the body is a example of excretion

Answer 3

Excretion is the removal of waste products of metabolism and substances in excess of requirements,and carbon dioxide is a waste product in aerobic respiration

Question 4

Why is carbon dioxide realised from respiration both a waste product and a useful product for plants

Answer 4

-during daylight hours,the carbon dioxide produced can be used to make carbohydrates in photosynthesis
-at night,they do not photosynthesise and so carbon dioxide is a waste product.

Question 5

Why should carbon dioxide be excreted

Answer 5

Carbon dioxide must be excreted as
-it dissolves in water easily to form an acidic solution which can lower the pH of cells
-This can reduce the activity of enzymes in the body which are essential for controlling the rate of metabolic reactions

Question 6

define urea

Answer 6

A waste product produced in the liver,from the breakdown of excess amino acids

Question 7

Define urine

Answer 7

A solution of urea and other waste materials in water,produced by the kidneys

Question 8

Define ureter

Answer 8

One of a pair of tubes that carries urine from the kidneys to the gall bladder

Question 9

Define urethra

Answer 9

The tube that carries urine from the gallbladder to the outside

Question 10

What part of the kidney takes the urine to the gall bladder

Answer 10

The ureter

Question 11

What are the substances filtered by the kidneys as blood passes through it

Answer 11

-urea
-excess water
-excess salts

Question 12

How is urea made in the liver (8 points)

Answer 12

1-protein in food is taken into the alimentary canal
2-the protein molecules are broken down to amino acids during digesting
3-the amino acids are absorbed into the blood and taken to the liver in the hepatic portal vein
4-amino acids that are needed are made into proteins in the liver or released into the blood to be assimilated by body cells
5-amino acids that are not needed are delaminated to carbohydrate and a nitrogen containing compound
6-the carbohydrates are used or stored in the liver
7-the nitrogen contains part is converted into urea
8-the urea to be excreted and the amino acids to be used by the body are taken away by the blood

Question 13

Define deamination

Answer 13

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

Question 14

Where is the kidney in the human body

Answer 14

At the back of the abdomen,behind the intestines

Question 15

Name 4 parts of the kidneys

Answer 15

-cortex
-medulla
-nephron
-ureter

Question 16

What is the function of kidneys

Answer 16

-they regulate the water content of the blood
-they excrete the toxic waste products of metabolism

Question 17

Where is the nephron located

Answer 17

Nephrons are located between the cortex and medulla

Question 18

What is a nephron

Answer 18

One of the thousands of microscopic tubes inside a kidney,where urine is made

Question 19

What gets filtered out of the blood and into the nephron

Answer 19

-water
-glucose
-ions
-urea

Question 20

What gets reabsorbed to the blood

Answer 20

-some water and ions
-glucose

Question 21

What is a glomerulus

Answer 21

A network of blood capillaries where the blood is filtered in a kidney

Question 22

What is the function for kidneys (name 2)

Answer 22

-they regulate the water content of the blood
-they excrete the toxic waste products of metabolism

Question 23

What is a cortex

Answer 23

The tissue making up the outer layer in a kidney

Question 24

What is a medulla

Answer 24

the tissue making up the inner layers in a kidney

Question 25

What are kidneys made out of

Answer 25

They are made out of thousands nephrons which starts at the coveted and loop down into the medulla and back up to the cortex which join to the ureter

Question 26

What gets filtered into the nephron

Answer 26

Small molecules such as:water,glucose,ions and urea are filtered out of the blood into the nephron

Question 27

What gets reabsorbed by blood

Answer 27

any useful substances such as water and glucose are taken back into the blood