Life Processes- Excretion

Question 1

define excretion

Answer 1

The biological
process involved in the removal of harmful metabolic wastes from
the body is called excretion

Question 2

how do unicellular organisms perform the activity of excretion

Answer 2

Many unicellular organisms remove these wastes by simple
diffusion from the body surface into the surrounding
water.

Question 3

list the components of the human excretory system

Answer 3

i) a pair of kidneys
ii) a pair of ureters
iii) urinary bladder
iv) urethra

Question 4

explain in brief what happens in the excretory system

Answer 4

. Kidneys are located in the
abdomen, one on either side of the backbone. Urine
produced in the kidneys passes through the ureters
into the urinary bladder where it is stored until it is
released through the urethra.

Question 5

what is the function of kidneys?
(or)
why is urine made?

Answer 5

The purpose of making
urine is to filter out waste products from the blood.
nitrogenous waste such as urea or uric acid are
removed from blood in the kidneys.

Question 6

define nephron

Answer 6

Nephrons are the structural and functional unit of kidney. They are a cluster of capillaries, along with some coiled tubes.

Question 7

what is the bowman’s capsule

Answer 7

Each capillary cluster in the kidney is
associated with the cup-shaped end of a coiled tube
called Bowman’s capsule that collects the filtrate

Question 8

what substabces are reabsrobed during formation of urine

Answer 8

Some substances in the initial filtrate, such as glucose,
amino acids, salts and a major amount of water, are
selectively re-absorbed as the urine flows along the tube.

Question 9

what does the amount of reabsorbed water depend upon

Answer 9

The amount of water re-absorbed depends on how much
excess water there is in the body, and on how much of
dissolved waste there is to be excreted.

Question 10

what makes the initial filtrarte

Answer 10

Bowman’s capsule encloses a bunch of capillaries called glomerulus. They together filter waste materials along with many useful substances.

Question 11

what is the function of the coiled tube

Answer 11

These regions absorb back useful substances into the blood and also filter remaining waste substances.

Question 12

what is the function of the collecting duct

Answer 12

the collecting duct collects the end product of the nephron, which is urine.

Question 13

what happens to formed urine in the kidneys

Answer 13

The urine forming
in each kidney eventually enters a long tube, the ureter,
which connects the kidneys with the urinary bladder.

Question 14

what is the function of the urinary bladder

Answer 14

Urine is stored in the urinary bladder until the pressure
of the expanded bladder leads to the urge to pass it out
through the urethra.

Question 15

why can we control the urge to urinate

Answer 15

The bladder is muscular, so it is
under nervous control, as we have discussed elsewhere.
As a result, we can usually control the urge to urinate.

Question 16

what are the main excretions of plants

Answer 16

Oxygen released during photosynthesis is used for respiration while carbon dioxide released during respiration is used for photosynthesis.Excretion of gaseous waste in plants takes place through stomatal pores on leaves.
Excess water is excreted by transpiration.

Question 17

how do plants take advantage of a large no of dead cells in tissues

Answer 17

plants use the fact that many of
their tissues consist of dead cells,
and that they can even lose some
parts such as leaves. Many plant
waste products are stored in
cellular vacuoles. Waste products
may be stored in leaves that fall off.

Question 18

what are some other ways in which plants excrete

Answer 18

Other waste products are stored as
resins and gums, especially in old
xylem. Plants also excrete some
waste substances into the soil
around them.