Matric Notes Biology Class 10th Ch 11 Homeostasis Long Questions
Q1: Describe the structure of kidneys in human beings?
Ans: Human kidney:
The human beings possess a pair of kidneys which are attached to the dorsal body wall in the abdominal cavity.
Color: Kidneys are dark brown in color.
Shape: Kidneys are bean shaped in structure and are enclosed in a thin membrane called peritoneum.
Size: Each kidney is 12 cm long, 6cm wide and 3cm thick.
Parts of kidney:
A longitudinal section of kidney shows that it consists of two regions.
Renal cortex: It is the outer darker region of the kidney.
Renal medulla: The inner lighter region of the kidney is called renal medulla.
Other regions of the kidneys are given below.
Hilus: The concave side of the kidney is called hilus. Hilus is the point where renal artery enters and renal vein leaves.
Pelvis: In the center of medulla there is a cavity which is funnel shaped, this is called pelvis. Pelvis is the upper expanded portion of urethra.
Units of kidney:
Kidney consists of millions of urinary tubules called nephron. A nephron is the structural and functional unit of kidney.
Q2: Why do plants excrete? What are the different mechanisms through which plants excrete different substances?
Ans: Excretion in plants:
Plants do not possess any special organs for excretion. They get rid-off different wastes in different ways, to maintain their internal environment. The materials which plants require to excrete are carbon dioxide produced during respiration, oxygen and water released as a byproduct of photosynthesis and some metabolic products like latex, resins and gums.
Excretion of carbon dioxide and oxygen:
During the day time, when active photosynthesis is going on, CO2 is retained in the leaves of plants and is used for photosynthesis. At night when there is no photosynthesis it is excreted through the open stomata of the leaves. During the day, the oxygen produced during photosynthesis is utilized in cellular respiration. The extra oxygen is released out through the stomata.
Excretion of extra water:
Plants store large amounts of water in the vacuoles of their cells. It results in turgor, which provides support to the soft parts of the body. If plants have extra amounts of water, they remove it in two ways.
i. Transpiration:
During day, plants remove their extra water by transpiration. There are three types of transpiration i.e. through the stomata (stomatal transpiration), cuticle (cuticular transpiration) and through lenticels (lenticular transpiration).
ii. Guttation:
Transpiration does not occur at night. Some plants such as grasses use a special method to remove extra water at night. They have pores at tips or edges of their leaves. They remove extra water through these pores, this water comes out in the form of little drops. This process is called guttation.
Excretion of other wastes:
Plants use different methods to excrete other wastes. Some plants store wastes in their bodies (stems, leaves or roots) in the form of harmless crystals. Some plants store their wastes in their leaves. When their leaves fall plant body also gets rid of these wastes. Some plants excrete their wastes through special pores by applying force. For example, the rubber plant excretes latex, the Acacia tree excrete gums, coniferous trees excrete resin, and the ladyfinger excrete mucilage.
Q3: What are kidney stone and how are they formed? Suggest ways in which these stones can be removed from the body?
Ans: Kidney stones:
Kidney stones are hard stone like materials called calculus which are collected in the kidneys.
Formation:
2: The most common type of kidney stone is calcium stones.
3: These stones are formed in metabolic disease like hyperkalemia (having high level of calcium ions in the blood).
4: They are also formed by hyperoxaluria having higher blood level of oxalates.
5: These are the contributing factors in the formation of calcium oxalate stones.
6: Oxalates are present in green vegetables and tomatoes.
7: Therefore eating green leafy vegetables and tomatoes may become source of hyperoxaluria.
Types of kidney stones:
There are four types of stones which have specific chemical nature. These types are:
ii. Uric acid stones
iii. Cysteine stones
iv. Stravide stones
Harmful effects:
2: They cause several pains.
3: They may stop the release of urine from kidney.
4: The disorder may become more complicated if infection occurs.
Treatment of kidney stones:
Take plenty of water:
If kidney stones are small in size, the patient is advised to drink plenty of water so that stones can pass through the urine.
Through surgery:
If stones are large and cannot pass easily, the patient has to undergo surgery. Patient’s kidney, ureter or urinary bladder is opened and stones are removed.
Non-surgical method:
The most recent method of removing kidney stones is called lithotripsy. It is the non-surgical removal of kidney stones. This technique is used to break up stones present in the kidney, ureter or urinary bladder.
Q4: Define haemodialysis. How is it performed?
Ans: Haemodialysis:
The word ‘hem’ means blood and dialysis means cleaning so hemodialysis mean cleaning of the blood. Procedure:
2: Dialyzer is also known as artificial kidney.
3: It has two spaces separated by a thin membrane.
4: Blood passes from one side of the membrane and dialysis fluid on the other side.
5: The nitrogenous wastes and excess water pass from the blood through thin membrane and into dialyzer by the process.
6: In this method the blood is cleaned by giving its wastes into dialysis fluid.
Q5: How does a dialyzer work? Relate the function of a dialyzer with that of the kidney?
ANS: Dialysis means separation, filtration or purification. In dialysis the patient blood is cleaned by passing it through a dialysis machine or by filtering it within the body through catheter. The dialysis machine is also known as artificial kidney or dialyzer.
Principles:
▪ Dialysis machine works on the same principles as human kidney. It removes the nitrogenous waste and extra water from the blood.
▪ It is used when kidney fails to work.
▪ Dialysis is done again and again but it is not a permanent treatment.
Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer that contains a semipermeable membrane.
Wastes and excess water move from the blood, across the peritoneal membrane and into a special dialysis solution, called dialysate, in the abdominal cavity.
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