NCERT Solutions for Class 10 Science Chapter 6 “Life Processes”
Answer Questions Page Number 95
1. Why is diffusion insufficient to meet
the oxygen requirements of multicellular organisms like humans?
Answer
:
Humans and other multicellular creatures have large
bodies and need a lot of oxygen to swiftly diffuse into the body in order to
meet their oxygen needs. The sluggish process of diffusion means that it will
take a long time for oxygen to reach every cell in the body. Diffusion moves
slowly, making it unable to supply the oxygen needs of multicellular organisms
such as humans.
2. What criteria do we use to decide
whether something is alive?
Answer
:
One can tell if something is alive or dead by
observing changes in its behaviour, such as growth, breathing, and walking. A
vital requirement to determine whether something is alive is the existence of
the life process, since some living objects undergo changes that are not
apparent to the naked sight.
3. What are outside raw materials used for
by an organism?
Answer
:
Organisms use the external raw material as food and
oxygen. The amount of raw resources needed depends on how sophisticated the
creature is and how it lives.
4. What processes would you consider
essential for maintaining life?
Answer
:
Life processes such as respiration, digestion,
excretion, circulation and transportation are essential for maintaining life.
Questions Page Number 101
1. What are the differences between
autotrophic nutrition and heterotrophic nutrition?
Answer
:
|
Autotrophic Nutrition |
Heterotrophic Nutrition |
|
Organism prepares its own food and is not dependent
on any other organism. |
An organism that does not prepare its own food and
is dependent on other organisms for food. |
|
Food is prepared from CO2, water, and
sunlight. |
Food cannot be prepared from CO2, water,
or sunlight. |
|
Chlorophyll is required for food preparation. |
Chlorophyll is not required for food preparation. |
|
Green plants and certain bacteria have autotrophic
modes of nutrition. |
All animals and fungi, most bacteria, have
heterotrophic modes of nutrition. |
2. Where do plants get each of the raw
materials required for photosynthesis?
Answer
:
The following is a raw material that plants need for
photosynthesis:
- Through
stomata, CO2 is drawn from the atmosphere.
- Plant
roots take up water from the earth.
- Sunlight
is a necessary component of photosynthesis.
- Plant
roots take up nutrients from the earth.
3. What is the role of the acid in our
stomach?
Answer
:
Food particles dissolve in the stomach’s HCl, which
also produces an acidic environment. Pepsinogen, an enzyme that breaks down
proteins, is transformed into pepsin in an acidic environment. Additionally,
the stomach’s HCl serves as a barrier of defence against numerous bacteria that
cause sickness.
4. What is the function of digestive
enzymes?
Answer
:
Simpler food molecules are formed from more complex
ones by digestive enzymes. This will facilitate and streamline the process of
food absorption. The blood carries food that has been absorbed throughout the
body.
5. How is the small intestine designed to
absorb digested food?
Answer
:
The microvilli, which are tiny projections found in
the small intestine, enhance the surface volume of the organ and improve
absorption. Many blood arteries found inside the villi take up and transport
digested food into the bloodstream. Food is carried to every area of our body
by blood.
Questions Page Number 105
1. What advantage over an aquatic organism
does a terrestrial organism have with regard to obtaining oxygen for
respiration?
Answer
:
While aquatic species take in oxygen that has been
dissolved in water, terrestrial organisms breathe by using oxygen found in the
atmosphere. Compared to the oxygen in the sea, there is a lot more oxygen in
the atmosphere. Therefore, although aquatic organisms must breathe more quickly
to receive the necessary oxygen, terrestrial species do not need to breathe
quickly to obtain organisms.
2. What are the different ways in which
glucose is oxidised to provide energy in various organisms?
Answer
:
Glycolysis is the process by which glucose is first
broken down in the cytoplasm into two molecules with three carbons each, called
pyruvate. distinct species undergo distinct processes that lead to further
degradation.
Answer
:
Humans’ bloodstreams are used to carry carbon dioxide and oxygen. While carbon dioxide is transported out of the cells, oxygen is transported into the cells. In the lungs, gas exchange occurs between the alveoli and the surrounding blood vessels. Diffusion occurs between the lungs’ alveoli and the blood capillaries to allow for the absorption of oxygen and carbon dioxide, respectively, by the alveoli.
4. How are the lungs designed in human
beings to maximise the area for the exchange of gases?
Answer
:
- One
vital organ in the body is the lung. The pulmonary route narrows and
narrows until it ends in formations known as alveoli, which resemble
balloons.
- The
alveoli offer a surface on which gas exchange is possible. A vast network
of blood arteries often lines the walls of the alveoli. We are aware that
inhaling causes our diaphragm to flatten, our ribs to rise, and our chest
cavity to expand.
- This
causes the air to be drawn into the lungs and fill the enlarged alveoli.
- The
blood feeds the alveoli with the necessary carbon dioxide that is carried
from the rest of the body; the blood in the alveolar blood vessels absorbs
the oxygen present in the alveolar air and delivers it to all other body
cells. The lungs always hold back air during the regular breathing cycle
when air is inhaled and exhaled, giving oxygen enough time to be absorbed
and carbon dioxide enough time to escape.
Questions Page Number 110
1. What are the components of the
transport system in human beings? What are the functions of these components?
Answer
:
The heart, blood and blood vessels are the main
components of the transport system in human beings.
Functions of these components
Heart
The heart pumps oxygenated blood throughout the body.
It receives deoxygenated blood from the various body parts and sends impure
blood to the lungs for oxygenation.
Blood
Blood transports oxygen, nutrients, CO2, and
nitrogenous wastes.
Blood vessels
Blood vessels, arteries and veins carry blood to all
parts of the body.
2. Why is it necessary to separate
oxygenated and deoxygenated blood in mammals and birds?
Answer
:
Warm-blooded creatures, mammals and birds maintain a
steady body temperature regardless of their living conditions. Warm-blooded
animals need a lot of oxygen for this process to occur because it increases
cellular respiration, which raises energy levels necessary for maintaining body
temperature. Therefore, maintaining the separation of oxygenated and
deoxygenated blood is crucial for warm-blooded species to maintain the
effectiveness of their circulatory system.
3. What are the components of the
transport system in highly organised plants?
Answer
:
Highly structured plants have two types of conducting
tissues that carry out the transport system. 1) Xylem 2) Poems. Water and
minerals are transported from the roots to the other plant components by xylem.
Phloem does a similar job of moving food components from the leaf to other
areas of the plant.
4. How are water and minerals transported
in plants?
Answer
:
A continuous network of water-conducting channels that
reaches every part of the plant is formed by the connections between the xylem
portions of the tracheids and the vessels of the roots, stems, and leaves. A
suction pressure produced by transpiration pushes water into the xylem cells of
roots. Water will then flow continuously from the root xylem to every area of
the plant that is connected by conducting, interconnected water-conducting
channels.
5. How is food transported in plants?
Answer
:
The phloem, a unique organ found in plants, is
responsible for carrying food. Food resources are transported from leaves to
various areas of a plant by phloem. The process of food transportation in
phloem involves the use of ATP energy. Water moves as a result of the tissue’s
increased osmotic pressure. Material in the Phloem is moved to the tissues
under reduced pressure by this pressure. This facilitates the transfer of food
supplies in accordance with needs. Sucrose, for instance
Questions Page Number 112
1. Describe the structure and functioning
of nephrons.
Answer
:
The filtration units of the kidney, known as nephrons,
are many. As the urine passes through the tube, some components of the original
filtrate—such as glucose, amino acids, salts, and a significant amount of
water—are selectively reabsorbed.
The main components of Nephrons are
Glomerulus
Bowman’s Capsule
Long Renal Tube
Structure of Nephron
The renal artery, which divides into many capillaries
connected to the glomerulus, is the pathway via which blood reaches the kidney.
At Bowman’s capsule, the solute and water are transported to the nephron.
Unwanted molecules are added to the urine and materials including amino acids,
glucose, and salts are selectively reabsorbed in the proximal tubule.
After that, the filtrate descends into the Henle loop, where further water is
absorbed. The filtrate then ascends into the distal tubule before arriving at
the collecting duct. Urine is collected from several nephrons by the collecting
duct.
Each kidney produces urine, which then passes into the ureter, a lengthy tube.
It travels from the ureter to the bladder and ultimately the urethra.
2. What are the methods used by plants to
get rid of excretory products?
Answer
:
Transpiration is a way for plants to expel extra
water.
Plants utilise the fact that many of their tissues are
made of dead cells and that they occasionally shed pieces of themselves, like
leaves, to get rid of other wastes. Cellular vacuoles are where many waste
products from plants are kept. Leaves that drop off can be used to store waste
materials.
Other waste materials are generally kept in old xylem
as resins and gums. Additionally, plants release certain waste materials into
the soil surrounding them.
3. How is the amount of urine produced
regulated?
Answer
:
The quantity of extra water and dissolved trash that
the body has determines how much urine is generated. The ADH hormone, which
controls urine output, and the surrounding conditions could also be important
variables.
Questions Page Number 113
1. The kidneys in human beings are a part
of the system for
(a) nutrition
(b) respiration
(c) excretion
(d) transportation
Answer
:
The answer is (c) excretion
A urine bladder, a urethra, two ureters, and two
kidneys make up the human excretory system (Fig. 6.13). There are two kidneys
in the abdomen: one on each side of the vertebrae. The ureters transport the
urine that the kidneys make into the bladder, where it is held until the
urethra opens.
2. The xylem in plants is responsible for
(a) transport of water
(b) transport of food
(c) transport of amino acids
(d) transport of oxygen
Answer
:
In plants, the Xylem is responsible for the transport
of water. Hence, the answer is (a)
3. The autotrophic mode of nutrition
requires
(a) carbon dioxide and water
(b) chlorophyll
(c) sunlight
(d) all of the above
Answer
:
The autotrophic mode of nutrition requires carbon
dioxide, water, chlorophyll and sunlight from the preparation of food. Hence,
the answer is (d) all of the above.
4. The breakdown of pyruvate to give
carbon dioxide, water, and energy takes place in
(a) cytoplasm.
(b) mitochondria
(c) chloroplast
(d) nucleus
Answer
:
The breakdown of pyruvate to give carbon dioxide,
water and energy take place in mitochondria. Hence, the answer is (b)
mitochondria
5. How are fats digested in our bodies?
Where does this process take place?
Answer
:
- The
whole breakdown of proteins, lipids, and carbohydrates takes place in the
small intestine. For this reason, it receives the pancreatic and liver
secretions.
- In
order for pancreatic enzymes to work on acidic food, which exits the
stomach, it must first be turned alkaline. This is done by the liver’s
production of bile juice.
- Larger
globules of fat are typically found in the colon, which makes it
challenging for enzymes to break down fats. Larger globules are broken
down into smaller globules with the assistance of the bile salts.
- Pancreatic
juice, which includes enzymes like trypsin for protein digestion and
lipase for the breakdown of emulsified lipids, is secreted by the
pancreas.
- There
are glands in the walls of the small intestine that release intestinal
juice. The enzymes in it ultimately break down proteins into amino acids,
complex carbs into glucose, and lipids into glycerol and fatty acids.
6. What is the role of saliva in the
digestion of food?
Answer
:
Our food is complex by nature, meaning it must be
broken down into smaller molecules in order for the alimentary canal to absorb
it. The primary biological catalysts used in this process are called enzymes.
Salivary amylase is an enzyme found in saliva that converts the complex
molecule starch to sugar. The food is extensively combined with saliva and
transported throughout the mouth when the tongue’s muscles are chewed. Saliva
is therefore essential to the breakdown and absorption of meals.
7. What are the necessary conditions for
autotrophic nutrition, and what are its byproducts?
Answer
:
- The
process of photosynthesis provides the autotrophic creature with the
energy and carbon it needs.
- It
is the process by which autotrophs absorb materials from their environment
and transform them into energy that is stored.
- This
material is ingested as carbon dioxide and water, which, when exposed to
sunshine and chlorophyll, transform into carbs.
- Carbs
are primarily used by plants as an energy source. Instead of being used
right away, the carbs are stored as starch, which acts as a kind of
internal energy reserve.
- The
plant can use the stored energy as and when it needs it.
8. What are the differences between
aerobic and anaerobic respiration? Name some organisms that use the anaerobic
mode of respiration.
Answer
:
Aerobic respiration
- The
process takes place in the presence of free oxygen.
- The
products of aerobic respiration are CO2, water and energy.
- The
first step of aerobic respiration (glycolysis) takes place in the
cytoplasm, while the next step takes place in mitochondria.
- The
process of aerobic respiration takes place in all higher organisms.
- In
this process, complete oxidation of glucose takes place.
Anaerobic respiration
- The
process takes place in the absence of free oxygen.
- The
products of anaerobic respiration are ethyl alcohol, CO2 and
a little energy.
- Even
in anaerobic respiration, the first step takes place in the cytoplasm,
while the next step takes place in mitochondria.
- In
this process, the glucose molecules are incompletely broken down.
- The
process of anaerobic respiration takes place in lower organisms like
yeast, some species of bacteria and parasites like tapeworms.
9. How are the alveoli designed to
maximise the exchange of gases?
Answer
:
- One
vital component of the body is the lung. The pulmonary route narrows and
narrows until it ends in formations known as alveoli, which resemble
balloons.
- The
alveoli offer a surface on which gas exchange is possible. A vast network
of blood arteries often lines the walls of the alveoli. We are aware that
inhaling causes our diaphragm to flatten, our ribs to rise, and our chest
cavity to expand.
- This
causes the air to be drawn into the lungs and fill the enlarged alveoli.
- The
blood feeds the alveoli with the necessary carbon dioxide that is carried
from the rest of the body; the blood in the alveolar blood vessels absorbs
the oxygen present in the alveolar air and delivers it to all other body
cells. The lungs always hold back air during the regular breathing cycle
when air is inhaled and exhaled, giving oxygen enough time to be absorbed
and carbon dioxide enough time to escape.
10. What would be the consequences of a hemoglobin deficiency in our bodies?
Answer
:
The protein known as haemoglobin is in charge of
delivering oxygen to body cells so they can respire. An inadequate amount of
haemoglobin may impact red blood cells’ ability to deliver oxygen. Our body’s
cells began to lack oxygen as a result of this. Anaemia is a condition caused
by a lack of hemoglobin.
11. Describe the double circulation of
blood in human beings.
Why is it necessary?
Answer
:
Double circulation means, in a single cycle, blood
goes twice in the heart. The process helps in separating oxygenated and
deoxygenated blood to maintain a constant body temperature.
The double circulatory system of blood includes
- Pulmonary
circulation
- Systemic
circulation.
Pulmonary circulation
Blood that has lost oxygen is pumped from the right
ventricle into the lungs, where oxygen is added. After being returned to the
left atrium, the oxygenated blood is pushed into the left ventricle. The aorta
receives blood at this point for systemic circulation.
Systemic circulation
The left ventricle pumps oxygenated blood to different
areas of the body. The vena cava is the conduit by which deoxygenated blood
from various bodily areas enters the right atrium. Blood is transferred from
the right atrium to the right ventricle.
12. What are the differences between the
transport of materials in the xylem and phloem?
Answer
:
|
Transport of Materials in Xylem |
Transport of Materials in Phloem |
|
Xylem tissue helps in the transport of water and
minerals. |
Phloem tissue helps in the transport of food. |
|
Water is transported upwards from roots to all other
plant parts. |
Food is transported in both upward and downward
directions. |
13. Compare the functioning of alveoli in
the lungs and nephrons in the kidneys with respect to their structure and
functioning.
Answer
:
|
Alveoli |
Nephrons |
|
Structure |
Structure |
|
(i) Alveoli are tiny balloon-like structures present
inside the lungs. |
(i) Nephrons are tubular structures present inside
the kidneys. |
|
(ii) The walls of the alveoli are one cell thick,
and it contains an extensive network of blood capillaries. |
(ii) Nephrons are made of glomerulus, Bowman’s
capsule, and a long renal tube. |
|
Function |
Function |
|
(i) The exchange of O2 and CO2 takes
place between the blood of the capillaries that surround the alveoli and the
gases present in the alveoli. |
(i) The blood enters the kidneys through the renal
artery. The blood is entered here, and the nitrogenous waste in the form of
urine is collected by the collecting duct. |
|
(ii) Alveoli are the site of gaseous exchange. |
(ii) Nephrons are the basic filtration unit. |
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