Lesson: Life Processes
Which
of the following statements about the autotrophs is incorrect?
(a)
They synthesise carbohydrates from carbon dioxide and water in the
presence of sunlight and chlorophyll.
(b)
They store carbohydrates in the form of starch.
(c)
They convert carbon dioxide and water into carbohydrates in the absence of
sunlight.
(d)
They constitute the first trophic level in food chains.
(c)
In
which of the following groups of organisms, food material is broken down outside
the body and absorbed?
(a)
Mushroom, green plants, Amoeba
(b)
Yeast, mushroom, bread mould
(c)
Paramecium, Amoeba, Cuscuta
(d)
Cuscuta, lice, tapeworm
(b)
Select
the correct statement
(a)
Heterotrophs do not synthesise their own food
(b)
Heterotrophs utilise solar energy for photosynthesis
(c)
Heterotrophs synthesise their own food
(d)
Heterotrophs are capable of converting carbon dioxide and
water
into carbohydrates
(a)
Which
is the correct sequence of parts in human alimentary canal?
(a)
Mouth → stomach → small intestine → oesophagus → large intestine
(b)
Mouth → oesophagus → stomach → large intestine small intestine
(c)
Mouth → stomach → oesophagus → small intestine → large intestine
(d)
Mouth → oesophagus → stomach → small intestine → large intestine
(d)
If
salivary amylase is lacking in the saliva, which of the following events in the
mouth cavity will be affected?
(a)
Proteins breaking down into amino acids
(b)
Starch breaking down into sugars
(c)
Fats breaking down into fatty acids and glycerol
(d)
Absorption of vitamins
(b)
The
inner lining of stomach is protected by one of the following from hydrochloric
acid. Choose the correct one
(a)
Pepsin
(b)
Mucus
(c)
Salivary amylase
(d)
Bile
(b)
Which
part of alimentary canal receives bile from the liver?
(a)
Stomach
(b)
Small intestine
(c)
Large intestine
(d)
Oesophagus
(b)
A
few drops of iodine solution were added to rice water. The solution turned
blue-black in colour. This indicates that rice water contains
(a)
complex proteins
(b)
simple proteins
(c)
fats
(d)
starch
(d)
In
which part of the alimentary canal food is finally digested?
(a)
Stomach
(b)
Mouth cavity
(c)
Large intestine
(d)
Small intestine
(d)
(d)
(b)
The
correct sequence of anaerobic reactions in yeast is
(d)
Which
of the following is most appropriate for aerobic respiration?
(d)
Which
of the following statement(s) is (are) true about respiration?
(i)
During inhalation, ribs move inward and diaphragm is raised
(ii)
In the alveoli, exchange of gases takes place i.e., oxygen from alveolar air
diffuses into blood and carbon dioxide from blood into alveolar air
(iii)
Haemoglobin has greater affinity for carbon dioxide than oxygen
(iv)
Alveoli increase surface area for exchange of gases
(a) (i) and (iv)
(b)
(ii) and (iii)
(c)
(i) and (iii)
(d)
(ii) and (iv)
(d)
Which
is the correct sequence of air passage during inhalation?
(a)
Nostrils → larynx → pharynx → trachea → lungs
(b)
Nasal passage → trachea → pharynx → larynx → alveoli
(c)
larynx → nostrils → pharynx → lungs
(d)
Nostrils → pharynx → larynx → trachea → alveoli
(d)
(b)
Which
of the following statement (s) is (are) true about heart?
(i)
Left atrium receives oxygenated blood from different parts of body while right
atrium receives deoxygenated blood from lungs
(ii)
Left ventricle pumps oxygenated blood to different body parts while right
ventricle pumps deoxygenated blood to lungs
(iii)
Left atrium transfers oxygenated blood to right ventricle which sends it to
different body parts
(iv)
Right atrium receives deoxygenated blood from different parts of the body while
left ventricle pumps oxygenated blood to different parts of the body
(a) (i)
(b)
(ii)
(c)
(ii) and (iv)
(d)
(i) and (iii)
(c)
(a)
Single
circulation i.e., blood flows through the heart only once during one cycle of
passage through the body, is exhibited by
(a)
Labeo, Chameleon, Salamander
(b)
Hippocampus, Exocoetus, Anabas
(c)
Hyla, Rana, Draco
(d)
Whale, Dolphin, Turtle
(b)
In
which of the following vertebrate group/ groups, heart does not pump oxygenated
blood to different parts of the body?
(a)
Pisces and amphibians
(b)
Amphibians and reptiles
(c)
Amphibians only
(d)
Pisces only
(d)
Choose
the correct statement that describes arteries.
(a) They have thick elastic walls, blood
flows under high pressure; collect blood from different organs and bring it
back to the heart
(b) They have thin walls with valves
inside, blood flows under low pressure and carry blood away from the heart to
various organs of the body
(c) They have thick elastic walls, blood
flows under low pressure; carry blood from the heart to various organs of the
body
(d) They have thick elastic walls without
valves inside, blood flows under high pressure and carry blood away from the
heart to different parts of the body.
(d)
(d)
Oxygen liberated during photosynthesis comes from
(a) water
(b) chlorophyll
(c) carbon dioxide
(d) glucose
(a)
(a)
Which of the following is an incorrect statement?
(a) Organisms grow with time
(b) Organisms must repair and maintain their
structure
(c) Movement of molecules does not take place among
cells
(d) Energy is essential for life processes
(c)
The internal (cellular) energy reserve in autotrophs
is
(a) glycogen
(b) protein
(c) starch
(d) fatty acid
(c)
Which of the following equations is the summary of photosynthesis?
(a)
(b)
(c)
(d)
(c)
(c)
(c)
(b)
(c)
(c)
Lack of oxygen in muscles often leads to cramps
among cricketers. This results due to
(a) conversion of pyruvate to ethanol
(b) conversion of pyruvate to glucose
(c) non-conversion of glucose to pyruvate
(d) conversion of pyruvate to lactic acid.
(d)
(c)
(a)
Name the following
(a) The process in plants that links light energy
with chemical energy
(b) Organisms that can prepare their own food
(c) The cell organelle where photosynthesis occurs
(d) Cells that surround a stomatal pore
(e) Organisms that cannot prepare their own food
(f) An enzyme secreted from gastric glands in
stomach that acts on proteins.
“All plants give out oxygen during day and carbon
dioxide during night”. Do you agree with this statement? Give reason.
Plants give out oxygen due
to photosynthesis. Photosynthesis is a process where plants use the Sun’s
energy to convert water and minerals into oxygen and various organic matter.
Therefore, during daytime, plants release oxygen. At night, plants give out
carbon dioxide due to lack of Sun’s energy.
How do the guard cells regulate opening and closing
of stomatal pores?
Guard
cells surround each stoma. When water enters the guard cells, they become
turgid and the stomatal pores opens. When water exits from guard cells, they
become flaccid and the stomatal pores close. This is how guard cells help
regulate opening and closing stomatal pores.
Two green
plants are kept separately in oxygen free containers, one in the dark and the
other in continuous light. Which one will live longer? Give reasons.
The plant
which is kept in continuous light will live longer, because it will be able to
produce oxygen required for its respiration by the process of photosynthesis.
If
a plant releases carbon dioxide and takes in oxygen during daytime, does it
mean that photosynthesis is not occuring? Justify your answer.
Plants
breathe throughout day and night. Photosynthesis
takes place only in presence of sunlight. Therefore, during day time, plants
release oxygen and at night they release carbon dioxide. However, if a plant
releases carbon dioxide and takes in oxygen during daytime, it means that the
rate of photosynthesis is slow. The carbon dioxide released during respiration
is used up for photosynthesis.
Why
do fishes die when taken out of water?
Fishes
breathe with the help of gills. Gills are designed to specifically inhale oxygen
that is dissolved in water, but are not designed to inhale oxygen from air. Therefore,
when a fish is taken out of water, it is unable to inhale oxygen in the air and
dies quickly.
Differentiate between an autotroph and a
heterotroph.
Autotroph |
Heterotroph |
|
They prepare their own food. |
They depend on other
organisms for food. |
|
They have chlorophyll. |
They lack chlorophyll. |
|
Is
‘nutrition’ a necessity for an organism? Discuss.
Yes,
nutrition is necessary for all organisms.
Importance
of nutrition
·
It provides
energy for various activities.
·
It is required
for growth of new cells.
·
It is required
for repair of damaged cells.
·
It helps fight
against various diseases.
What would
happen if green plants disappear from Earth?
Green
plants are the direct or indirect sources of energy for all organisms. Green
pants help transfer solar energy to other organisms. If all green plants
disappear from Earth, all the herbivores will die of starvation and as a ripple
effect, all the carnivores will also die. This will eventually lead to extinction of
life from Earth.
Leaves of
a healthy potted plant were coated with vaseline. Will this plant remain
healthy for long? Give reasons for your answer.
The vaseline
coat will create an impermeable layer on the leaves. This will clog the stomata
and the leaves will not get oxygen for respiration. Also, photosynthesis will
not occur. As a result, the plant will not be able to prepare its food. Eventually,
the plant will slowly die.
How does
aerobic respiration differ from anaerobic respiration?
Aerobic respiration |
Anaerobic respiration |
Occurs in the presence of oxygen. |
Occurs in the absence of oxygen. |
Takes place in cytoplasm (glycolysis) and inside mitochondria (Krebs cycle) |
Takes place only in cytoplasm. |
End products are carbon dioxide and water. |
End products are lactic acid or ethanol and carbon dioxide. |
More energy is released. |
Less energy is released. |
Match the
words of Column (A) with that of Column (B)
Column (A) |
Column (B) |
(a) Phloem |
(i) Excretion |
(b) Nephron |
(ii) Translocation of food |
(c) Veins |
(iii) Clotting of blood |
(d) Platelets |
(iv) Deoxygenated blood |
(a) (ii)
(b) (i)
(c) (iv)
(d) (iii)
Differentiate
between an artery and a vein.
Artery |
Vein |
Have thick elastic, muscular walls. |
Have thin, non-elastic walls. |
Valves are absent. |
Valves are present. |
Carry blood from heart to
all body parts. |
Carry blood from all body parts to heart. |
Carry oxygenated blood
(except pulmonary artery). |
Carry deoxygenated blood (except pulmonary vein) |
What are the adaptations of leaf for photosynthesis?
Leaves show following adaptations for photosynthesis:
(a) Leaves provide large
surface area. This helps absorbing maximum light.
(b) Leaves are arranged at
right angles to the light source. This helps in absorbing maximum light.
(c) Leaves have extensive network of veins. This
enables quick transport of substances to and from the mesophyll cells.
(d) Leaves have numerous stomata for gaseous
exchange.
(e) The upper surface of
leaves have more number of chloroplasts. Chloroplasts enable photosynthesis.
Why is
small intestine in herbivores longer than in carnivores?
Digestion of cellulose
takes longer time. Herbivores eat grass, and therefore need a longer small
intestine to allow complete digestion of cellulose. In case of carnivores,
cellulose is not present in their diet, because they eat a protein rich diet
that can be easily digested. Therefore, the small intestine of herbivores is
longer than that of carnivores.
What will
happen if mucus is not secreted by the gastric glands?
Mucus
protects the inner lining of stomach from hydrochloric acid. If mucus is not secreted,
the inner lining of stomach will be corroded by hydrochloric acid leading to acidity
and ulcers.
What is
the significance of emulsification of fats?
Food, fats
are present in the form of large molecules that make it difficult for the
digestive enzymes to act on them. Emulsification of fat breaks down large fat
molecules into small molecules, making it easy for the digesting enzymes to
digest the fat.
What causes movement of food inside the alimentary
canal?
Why is digested food absorbed mainly in the small
intestine?
The wall
of the small intestine contains glands that secrete intestinal juice. This intestinal
juice contains a number of enzymes that help in digestion.
Liver
provides villi to the inner lining of the small intestine. This increases the
surface area for absorption. The blood vessels in the walls of small intestine
take the absorbed food to each cell of the body.
Match Group (A) with Group (B)
Group (A) |
Group (B) |
a) Autotrophic nutrition |
(i) Leech |
(b) Heterotrophic nutrition |
(ii) Paramecium |
(c) Parasitic nutrition |
(iii) Deer |
(d) Digestion in food vacuoles |
(iv) Green plant |
(a) (iv)
(b) (iii)
(c) (i)
(d) (ii)
Why is the
rate of breathing in aquatic organisms faster than in terrestrial organisms?
Air is not
available in large quantity under water and aquatic organisms obtain oxygen in
a dissolved state. Since the amount of dissolved oxygen is fairly low, aquatic
organisms have to put more effort to breathe oxygen to meet their needs. On the
other hand, because of good availability of oxygen in air, terrestrial
organisms do not need to put too much effort to breathe. Therefore, aquatic
organisms breathe much faster than terrestrial organisms.
Why is
blood circulation in human heart called double circulation?
During one
cardiac cycle, blood passes through a human heart twice. Once through the right
half in the form of deoxygenated blood and secondly through the left half in
the form of oxygenated blood. Thus, blood circulation in human heart is called
double circulation.
What is the advantage of having a four chambered
heart?
A
four chambered heart prevents oxygenated and deoxygenated blood from mixing. Blood
is received by the upper chambers from rest of the body and is pumped out back
to the body by the lower chambers. This segregation between blood received by
the heart and then sent out again increases the efficiency of the heart.
Mention the major events during photosynthesis.
The major events during photosynthesis are:
(a) Absorption of sunlight (energy) by chlorophyll.
(b) Conversion of light energy into chemical energy and splitting of water
into hydrogen and oxygen.
(d) Reduction of carbon dioxide by hydrogen to form carbohydrates.
In each of
the following situations what happens to the rate of photosynthesis?
(a) Cloudy
days
(b) No
rainfall in an area
(c) Good
manuring in an area
(d)
Stomata get blocked due to dust
(a)
Decreases
(b)
Decreases
(c)
Increases
(d)
Decreases
Name the
energy currency in all living organisms. When and where is it produced?
Adenosine
triphosphate (ATP) is the energy currency in all living organisms. It is produced
during respiration in the mitochondria. It is also produced during
photosynthesis.
What is
common for cuscuta, ticks and leeches?
The given
examples belong to parasites. They derive nutrition from plants or animals
without killing them.
Explain
the role of mouth in digestion of food.
Mouth
plays the following roles in the digestion of food:
(a) Food is crushed into smaller pieces by the teeth.
So that it become easier to swallow the food.
(b) The smaller food particles are then mixed with
saliva. The enzyme amylase (found in saliva) breaks down the starch into
sugars.
(c) Tongue plays the important role of mixing food with
saliva.
What are
the functions of gastric glands present in the wall of a stomach?
Functions
of gastric glands:
(a) They produce gastric acid.
(b) They release gastric enzyme pepsin to digest
proteins.
(c) They secret mucus to protect the inner lining of a stomach.
Match the
terms in Column (A) with those in Column (B)
Column (A) |
Group (B) |
a) Trypsin |
(i) Pancreas |
(b) Amylase |
(ii) Liver |
(c) Bile |
(iii) Gastric glands |
(d) Pepsin |
(iv) Saliva |
(a) i
(b) iv
(c) ii
(d) iii
Name the correct substrates for the following
enzymes
(a) Trypsin
(b) Amylase
(c) Pepsin
(d) Lipase
(a) Protein
(b) Starch
(c) Protein
(d) Fats
Why do
veins have thin walls as compared to arteries?
Arteries are thick-walled
blood vessels. It carries blood from heart to all parts of a body. The blood that
emerges from heart is under high pressure. Therefore, to control the pressure,
the walls of the arteries have to be thick. Veins collect blood from different
organs of the body and carry it to the heart. Veins do not need thick walls as
the blood is no longer under high pressure.
What will happen if platelets were absent in blood?
Platelets in blood help in blood clotting.
Therefore, absence of platelets will reduce blood clotting causing excessive
blood flow during an injury. This might lead to death.
Plants have low energy needs as compared to
animals. Explain.
Animals need to move from one place to another in
search of food. Plants, on the other hand, do not move. Therefore plants require
less energy as compared to animals.
Why and how does water enter continuously into the
root xylem?
Root cells are in close contact with soil. They actively take up ions. The
osmotic pressure at the roots of a plant is more than the pressure at the
leaves due to high ion concentration inside the root. This pressure difference continuously
increases the movement of water from the soil into the root xylem.
Why is
transpiration important for plants?
Transpiration
helps in absorption and upward movement of water and minerals from roots to
leaves. It prevents plant parts from heating up. Also, it is a way for plants
get rid of excess water.
How do
leaves of plants help in excretion?
Many
plants store their waste materials in leaves, barks, and fruits. When dead
leaves fall off from a plant, these waste materials also get excreted. Apart
from this, gaseous waste in plants is removed through stomata in leaves.
Explain
the process of nutrition in Amoeba.
Amoeba is
a unicellular organism which follows holozoic mode of nutrition. The cell
membrane of an amoeba keeps on protruding into temporary finger-like
extensions, which surrounds food particles and form a food vacuole. Inside the
food vacuole, complex food substances are digested into simpler substances with
the help of digestive enzymes. After that, the digested food is diffused into
the cytoplasm. Finally, the remaining undigested food material is moved to the
surface of the cell and expelled out.
Describe
the alimentary canal of man.
The human
alimentary canal is basically a long tube extending from the mouth to the anus.
Mouth: It
consists of oral cavity, through which food is ingested. It contains teeth,
tongue and three pairs of salivary glands.
Oesophagus:
It is also known as food pipe. It begins from the neck and ends in the stomach.
The muscular movement of the oesophagus called peristalsis carries the food
down to the stomach.
Stomach: Stomach
is a bag-like organ. It is a large organ which expands when food enters into it.
The highly muscular walls of the stomach help in churning the food thoroughly
with more digestive juices.
Small Intestine: It is a highly coiled
tube-like structure. It is divided into three parts, namely duodenum, jejunum
and ileum.
Large Intestine: The ileum passes into large
intestine. It is smaller than the small intestine and the undigested food goes
into it. The large intestine is further divided into two parts as anterior
colon and posterior rectum. The terminal part of rectum is called anal canal.
It opens into the anus, guarded by sphincter muscles. It allows the waste
matter to be excreted.
Explain
the process of breathing in man.
Breathing
is the process of taking in oxygen-rich air and giving out carbon dioxide-rich
air.
Breathing
in humans involves following steps:
·
Inhalation: When
we breathe in, the muscles between the ribs contract causing the ribcage to
move upward and outward. Simultaneously, the diaphragm contracts and moves
downward. As the chest cavity size increases, air is sucked in from outside
into the lungs, the lungs get filled up with air and expand. Thus, the size of
our chest increases. Breathing is the process of taking in oxygen-rich air and
giving out carbon dioxide-rich air.
·
Gaseous
exchange: Haemoglobin in the red blood cells binds with oxygen and carries it
through blood. During respiration, blood passes through the tissues of a body,
the oxygen from the blood diffuses into various cells and carbon
dioxide produced diffuses into the blood. The carbon dioxide-rich
blood is carried to the lungs.
·
Exhalation:
When we breathe out, the muscles between the ribs relax causing the ribcage to
move back and the diaphragm relaxes and moves upward. As the chest cavity
becomes smaller, carbon dioxide-rich air is pushed out from the lungs.
Explain
the importance of soil for plant growth.
Soil
provides the base on which all terrestrial plants and even some aquatic plants
grow. Soil is the reservoir of water and minerals essential for all metabolic
activities of a plant. The roots of a plant take oxygen required for
respiration from soil by process of diffusion. Some plants form symbiotic
relationship with soil microbes and absorb minerals such as nitrogen. For
example, leguminous plants form symbiotic relationship with the soil because it
absorbs minerals from soil.
Draw the
diagram of alimentary canal of man and label the following parts.
Mouth, Oesophagus,
Stomach, Intestine
How do
carbohydrates, proteins and fats get digested in human beings?
Digestion of carbohydrates:
Digestion
of carbohydrates starts from the mouth cavity. The saliva secreted in the mouth
cavity contains the salivary amylase. It breaks down starch into simple sugar.
Other
forms of carbohydrates are digested in small intestine.
Digestion of Proteins:
Partial
digestion of protein takes place in stomach with the help of a gastric enzyme called
pepsin. Further digestion of protein happens in small intestine.
Digestion of Fat:
Fat is at
first emulsified by bile and then digested by small intestine.
Explain
the mechanism of photosynthesis.
Photosynthesis
is a process by which green plants prepare their own food.
During
photosynthesis,
·
Sunlight is
absorbed by chlorophyll.
·
Light energy is
then converted into chemical energy.
·
Water is
absorbed from soil and transported to leaves with the help of roots and stem.
Then water molecule splits into hydrogen and oxygen.
·
Oxygen, which
is the by-product of photosynthesis is released into air.
·
Hydrogen is used
for reduction of carbon dioxide to form carbohydrate (glucose) by
utilizing the chemical energy. Carbon dioxide enters the
leaves from air through tiny pores called stomata.
·
The extra
glucose is stored as starch in the leaves of a plant.
The whole process of photosynthesis can be shown by
following equation:
Explain
the three pathways of breakdown in living organisms.
In the
process of respiration, the first step is breakdown of glucose into pyruvate.
This process takes place in the cytoplasm. The molecules formed depend on the
type of respiration in a particular organism. Respiration is of two types,
aerobic respiration and anaerobic respiration.
·
Anaerobic
Respiration: This process takes place in absence of oxygen. For example, during
yeast fermentation, pyruvate is converted into ethanol and carbon dioxide.
·
Aerobic
Respiration: In this type of respiration, breakdown of pyruvate takes place in
the presence of oxygen. Hence, optimum output of energy is achieved. The
release of energy in aerobic respiration is much more than anaerobic
respiration.
Describe
the flow of blood through the heart of human beings.
After systemic
circulation through-out the body, blood flows into the right auricle of the
heart. From the right auricle, the heart, pumps blood into the right ventricle.
From the right ventricle, heart pumps blood to lungs through pulmonary artery.
Oxygenation of blood takes place in alveoli inside lungs. This oxygenated blood
from the lungs flows into the left auricle through pulmonary vein. From left
auricle, heart pumps blood into the left ventricle. Finally, from the left
ventricle, heart pumps out blood to the body for another round of systemic
circulation.
This whole process is repeated continuously. The
circulatory system in humans is called double circulation. This is because blood
flows twice through the heart during one complete cycle.
Describe
the process of urine formation in kidneys.
Urine is
formed in the kidneys. Nephrons are the structural and functional units of
kidneys. Each kidney possesses large number of nephrons, approximately 1-1.5
million. The main components of the nephron are glomerulus, Bowman's capsule,
and a long renal tubule.
The following steps are involved in the formation
of urine:
(i) Filtration: Blood enters the kidney through the
renal artery that branches into many capillaries associated with glomerulus.
The filtration of blood takes place in Bowman's capsule under very high
pressure. Large molecules remain in the blood.
(ii) Selective reabsorption: Some molecules are
selectively reabsorbed into the blood. Then the filtrate flows through the
proximal convoluted tubule, the U-shaped Henle’s loop and distal convoluted
tubule. After substances such as glucose, amino acids, and salts are reabsorbed,
the filtrate now contains urea, some salts and water. Reabsorption of solutes
increases the water concentration of the filtrate.
(iii)
Tubular
secretion: Some nitrogenous waste products like creatinine are removed from
blood and are added to urine. Then the filterate goes to the collecting duct. The
collecting duct collects urine from many nephrons. The urine formed in each
kidney enters a long tube called ureter. From ureter, it gets transported to
the urinary bladder and then into the urethra.