UNIT 1 PLANT
SYSTEM
SOLUTION OF EXERCISES AT THE END OF UNIT
A Choose the correct option.
(1) Which root system can get water from
deep underground sources?
(a)
fibrous roots (b) tap roots
(c)
storage roots (d) root nodules
Answer: -
(b) tap roots
(2) Which of the following is not an organ
of plant?
(a)
stomata (b) root (c) stem (d) leaf
Answer: -
(a) stomata
(3) Vascular bundles are present in every
part of the plant. They are made of
(a)
xylem only (b) phloem only
(c)
xylem and phloem
(d) xylem,
phloem and root hair cells
Answer: -
(c) xylem and phloem
(4) Aliya dropped a spoon of sugar in a
glass of water and forgot about it. After few hours when she tasted that water
it was sweet, due to
(a)
movement of sugar molecules from area of low concentration to high
concentration.
(b) movement of sugar molecules from
area of high concentration to low concentration.
(c)
movement of water molecules due to wind.
(d)
swelling of sugar molecules.
Answer: - (b) movement of sugar
molecules from area of high concentration to low concentration.
(5) If water available to plants become
less, then stomata are closed even daytime. This protects plants from
(a)
photosynthesis. (b) respiration.
(c)
wilting (d)
transport of water.
Answer: -
(c) wilting.
(6) A goat ate all the leaves of a small
shrub. In few days the plant dried although it was watered regularly. The main reason
could be that without leaves plant cannot
(a)
make food (b) store food
(c)
transport food (d) do respiration
pull
Answer: -
(a) make food
(7) If the concentration of carbon dioxide
increases in the air during daytime the process of
(a)
photosynthesis will decrease.
(b)
respiration will decrease.
(c)
photosynthesis will increase.
(d)
respiration will increase.
Answer: -
(c) photosynthesis will increase.
(8) Hassan was sitting under a tree shade
on a hot day. When he looked up, he noticed that all leaves of the tree were
arranged at angles so that
(a)
all the leaves can get sunlight.
(b) all the
leaves get rain water.
(c) trees can
give proper shade.
(d) all leaves
can stay away from each other.
Answer: -
(a) all the leaves can get sunlight.
(9) If you stay under trees at night, you
can feel dizziness due to
(a)
high level of oxygen and low level of carbon dioxide.
(b)
low level of oxygen and high level of carbon dioxide.
(c)
toxic gases released by trees.
(d)
ghosts living in trees.
Answer: -
(b) low level of oxygen and high level of carbon dioxide.
(10) Which of the following is the correct
word equation for photosynthesis?
(b)
(c)
(d)
Answer
(b)
B True or False (correct the statement if it is False).
(a) Exchange of gases
in plants take place through tiny holes called stomata located on the margins
of leaves.
Answer: -
True.
(2) The rate of
photosynthesis is slow in variegated leaves because there is maximum amount of
chlorophyll in them.
Answer: -
False. The rate of photosynthesis is slow in variegated leaves because there is
minimum amount of chlorophyll in them.
(3) Respiration can only
take place in animal cells because they need energy.
Answer: -
False. Respiration can take place in plant and animal cells because they need
energy.
(4) The job of root
hairs is to protect the roots from damage.
Answer: -
False. The job of root hairs is to absorb water and minerals from the soil.
(5) Xylem is dead
tissue while phloem is living tissue.
Answer: -
True
C Give short answers to the following questions.
(a) What are three
functions of roots?
Answer: -
The functions of roots are as under.
(i) They absorb water and minerals
from the soil by the process of diffusion.
(ii) They provide support in
anchoring of the plant body to ground.
(iii) They transport water and
minerals to stem.
(iv) They store food and minerals.
(2) Plant stems are of
many types. Name any three types of stem with examples.
Answer: -
There are three types of stems depending on the location of stem with respect
to ground.
Underground Stems: -
These stems remain at ground and produce aerial shoots above the soil. The
examples of underground stems are taro corm, ginger and potatoes.
Aerial Stems: -
These stems are found above the ground and perform different functions. The
examples of aerial stems include Durante and Carissa are examples of aerial
stems.
Subaerial Stems:
-
These stems run parallel to the ground and give off roots at certain intervals
or nodes. The examples of subaerial stems include runner of oxalis, wood-sorrel,
stolon of wild strawberry and sucker of rose etc.
(3) Why does water move
upwards through xylem in day time?
Answer: -
As water evaporates from the leaves, it creates shortage of water and it is
pulled up from the soil through the xylem to overcome this shortage. The higher
the rate of loss of water through the leaves the higher will be pulling of
water from soil.
(4) How stomata help in
the process of photosynthesis?
Answer: -
The stomata controls the entrance of carbon dioxide in the leaf, the release of
oxygen and the flow of water out of the leaf. These parameters are essential
for photosynthesis process. Thus, stomata control the rate of photosynthesis.
(5) What is the
importance of chlorophyll for plants?
Answer: -
Chlorophyll resides in the chloroplasts of plants and is a green pigment.
Chlorophyll is essential for plants to convert carbon dioxide and water, in the
presence of sunlight, to convert into glucose and oxygen. No photosynthesis
will take place in the absence of chlorophyll.
D Give detailed answers to the following questions.
(1) Compare the
properties of xylem and phloem.
Answer
|
Xylem |
Phloem |
|
Xylem
are made of dead tissues. In trees new xylem is made each year forming rings
in the tree trunk. |
Phloem
are made of living tissues. |
|
Xylem
have thick and strong cell walls. |
Phloem
have thin cell walls. |
|
It
transports water and dissolved minerals from the roots to the leaves through
the stem. |
It
transports food in the form of sugar solution from leaves to all other parts
of the plant. |
|
Direction
of flow water and dissolved minerals is only in the upward direction. |
Sugar
solution can move in both directions i.e. in upward and downward direction |
(2) How is
photosynthesis important for:
(a) plants (b)
humans and other animals
(c) atmosphere
Answer
(a) Importance of
Photosynthesis for Plants
Plants prepare their food in the
form of glucose by photosynthesis which is essential for their life and growth.
In the absence of photosynthesis, they are unable to prepare their food and
will ultimately die.
(b) Importance of
Photosynthesis for Humans and other Animals
Living things cannot survive
without food and oxygen. Photosynthesis is the only chemical process during
which plants prepare food and oxygen for themselves and for all other living
things. The plants and their by-products such as fruits etc. are used as food
by animals and humans as their food which is vital for their survival. The oxygen released in photosynthesis is also used by
all living things for respiration. If there is no food then there will be no
life on planet Earth.
(c) Importance of
Photosynthesis for Atmosphere
During photosynthesis, plants use
light energy from the Sun, carbon dioxide from air and water from the soil to
make glucose and oxygen. The absorption of carbon dioxide and release of oxygen
in photosynthesis helps to maintain a balance of these gases in air. Hence
photosynthesis is very important for atmosphere.
(3) Photosynthesis and
respiration are two different processes. Differentiate between them.
Answer
|
Photosynthesis |
Respiration |
|
In
photosynthesis plants use carbon dioxide and water in the presence of
sunlight to produce glucose and oxygen. |
In
respiration process oxygen and glucose are used to power the activities of
cells and carbon dioxide and water are released. |
|
It
takes place during the day. |
It
takes place day and night. |
|
It
takes place only in plants. |
It
takes place in all living things i.e. plants, animals and humans. |
|
Energy
is stored. |
Energy
is released. |
Constructed Response Questions
(1) The rate of photosynthesis in
aquatic plants at different temperatures was investigated. The findings are
shown in the following graph.
(a) How does the
temperature from
Answer: -
The rate of photosynthesis increases with increase in temperature for
(b) At what temperature
is the rate of photosynthesis the highest?
Answer: -
The rate of photosynthesis is highest at
(c) When the temperature is increased beyond
Answer: -
The rate of photosynthesis decreases as
the temperature is increased beyond
(2) The table shows the
transpiration rate of plants in different conditions.
|
Condition |
Transpiration rate
(mm/min) |
|
Darkness |
1 |
|
Bright light |
17 |
|
Still air |
9 |
|
Moving air |
21 |
|
Dry air |
11 |
|
Moist air |
5 |
|
Warm air |
16 |
|
Cold air |
6 |
|
Dry soil |
2 |
|
Moist soil |
18 |
(a) What condition
causes the fastest rate of transpiration?
Answer: -
Moving air
(b) How much greater is
the transpiration rate in moist soil than in dry soil?
Answer: -
(c) What sort of
condition can increase the rate of transpiration?
Answer: -
The conditions like bright light, moving air, dry air, warm air and moist soil
can increase the rate of transpiration.
(d) How does
transpiration help in the water cycle?
Answer: -
The loss of water from the stomata is called transpiration.
Do you know? (Page 07)
Diffusion is the movement of
molecules from their area of higher concentration to lower concentration.
Science Titbits (Page 07)
Do you know? (Page 06)
In desert plants like cactus thick
stem store water and become green to perform photosynthesis.
Science Titbits (Page 08)
Sargodha has the largest tree in
Pakistan. This, Banyan tree is amazing with over one thousand roots and covers
an area of approximately three acres.
Do you know? (Page 12)
Leaf structure is best suited for
the process of photosynthesis to the following adaptations:
·
Broad
and flat shape to help absorption of sunlight and carbon dioxide,
·
Thin
to help diffusion of gases.
·
Large
air spaces for easy movement of gases.
·
Large
number of stomata for exchange of gases.
·
Network
of veins to supply water to the cells.
·
Transparent
epidermis to allow entry of light.
·
Waxy
cuticle to slow water loss.
·
Large
number of chloroplasts in photosynthesis cells.
·
Starch
formation in leaf cells.
ADDITIONAL
OBJECTIVE QUESTIONS
MULTIPLE CHOICE QUESTIONS (MCQ)
Four options are
given for each question. Choose the correct option.
(1) How many main types of roots
are there?
Answer:
-
(b) 2
(2) A taproot system has
(a)
primary roots (b) secondary roots
(c)
tertiary roots (d) all of
these
Answer: -
(d) all of these
(3) The outer most layer of a leaf
is called
(a)
midrib (b) veins
(c)
an epidermis (d)
stomata
Answer: -
(c) an epidermis
(4) How many guard cells surround a
stoma?
(a) 1 (b) 2 (c) 3 (d) 4
Answer: -
(b) 2
(5) The loss of water from surface
of leaves is called
(a)
transportation (b)
transpiration
(c)
translocation (d) transplantation
Answer: -
(b) transpiration
(6) The transport system of a plant
consists of network of tubes called
(a) xylem (b)
phloem
(c)
xylem and phloem (d)
none of these
Answer: -
(c) xylem and phloem
(7) The xylem transports
(c)
water and dissolved minerals
(d)
food and dissolved minerals
Answer: -
(c) water and dissolved minerals
(8) The phloem transports
(a)
food (b)
water
(c) water and
dissolved minerals
(d) food and
dissolved minerals
Answer: -
(a) food
(9) Which of the following is
responsible for absorption of light in plants?
(a)
Xylem (b) Phloem
(c)
chlorophyll (d)
stoma
Answer: -
(c) chlorophyll
(10) Which of the following gas is
absorbed by the leaf of a plant in photosynthesis process?
(a)
hydrogen (b) oxygen
(c)
carbon dioxide (d) nitrogen
Answer: -
(c) carbon dioxide
(11) Which of the following gas is
released by the leaf of a plant in photosynthesis process?
(a)
hydrogen (b) oxygen
(c)
carbon dioxide (d) nitrogen
Answer: -
(b) oxygen
(12) The repair of plant cells
takes place
(a)
during day time (b) during night
(c)
only at mid-day (d) all the time
Answer: -
(d) all the time
(13) Which of the following gas is
needed for the repair of plant cell?
(a)
Hydrogen (b) Nitrogen
(c)
Oxygen (d) Carbon
dioxide
Answer: -
(c) Oxygen
State whether
the given statement is true or false. Correct the statement if it is false.
(1) The roots of a
plant spread in the soil and anchor it.
Answer: -
True.
(2) The branches of secondary roots are
called primary roots.
Answer: -
False. The branches of secondary roots are called tertiary roots.
(3) The stem does not
give support to the plant.
Answer: -
False. The stem gives support to the plant.
(4) In a stem,
vascular bundles are arranged like a ring, just above the epidermis.
Answer: -
False. In a stem, vascular bundles are arranged like a ring, just beneath the
epidermis.
(5) Each leaf has many
midribs and a central vein.
Answer: -
False. Each cell has a central midrib and many veins.
(6) The process of photosynthesis does
not take place in leaves.
Answer: -
False. The process of photosynthesis takes place in leaves.
(7)
The outer most layer of a leave is called an epidermis.
Answer:
-
True
(8)
There is a water proof covering over epidermis called cuticle.
Answer:
-
True
(9)
Stomata open during night time and close at day time.
Answer:
-
False. Stomata open during day time and close at night time.
(10) The xylem transports water and
dissolved minerals from the leaves to the roots through the stem.
Answer: -
False. The xylem transports water and
dissolved minerals from the roots to the leaves through the stem.
(11) The phloem transports food in the
form of sugar solution from leaves to all other parts of the plant.
Answer: -
True.
(12) The necessary factors for
photosynthesis are light, chlorophyll, carbon dioxide, water and suitable
temperature.
Answer: -
True
(13) Photosynthesis
process can take place at night time.
Answer: -
False. Photosynthesis process cannot take place at night time.
(14) The respiration process takes place
in the mitochondria of a plant cell.
Answer: -
True
Give short
answer to the following questions.
(1) What is meant by
diffusion?
Answer: -
Diffusion is the movement of molecules from their area of higher concentration
to lower concentration.
(2) Differentiate
between root and shoot system of a plant.
Answer: - The
part of a plant which is underground is called root system and the its part above
the ground is called shoot system of the plant.
(3) What is a taproot
system? Give examples.
Answer: -
A taproot system has one main root called primary root that grows downward.
Many plants, trees and shrubs have taproot system.
(4) Define fibrous roots.
Give examples.
Answer: -
Fibrous roots are thread-like structures that spread out from the base of the
stem of a plant. Grasses and wheat have fibrous roots.
(5) What are different
parts of shoot system of a plant?
Answer: -
The shoot system of a plant has stem, leaves, flowers and fruits.
(6) Describe the
function of stem of a plant.
Answer: -
The stem gives support to the plant. It transports substances between the roots
and aerial parts of the plant including leaves, flowers and fruits.
(7) What is the
herbaceous plant? Give examples.
Answer: -
Plants with green and flexible stem are called herbaceous plants. Daisies,
grass and crops are examples of herbaceous plants.
(8) What is meant by a
woody plant? Give examples.
Answer: -
A plant with hard and strong stem is called a woody plant. Trees, shrubs and
most vines are examples of woody plants.
(9) Briefly describe a
leaf.
Answer: -
The flat green portion of a leaf is called leaf blade. Each leaf has a
central midrib and many veins. Midrib is the extension of leaf stalk.
The midrib and veins provide support to the leaf. They contain vascular bundles
to transport substances to and from the leaves.
(10) Where does
photosynthesis process take place?
Answer: -
The photosynthesis process takes place in leaves.
(11) What would happen if the leaves of
a plant are covered with water-proof petroleum jelly?
Answer: -
If the leaves of a plant are covered with water-proof petroleum jelly then
stomata present in leaves will not be able to open and no respiration will take
place. As a result, the plant will die.
(12) What is the function of the xylem?
Answer: - The xylem
transports water and dissolved minerals from the roots to the leaves through
the stem.
(13) What is the function of phloem?
Answer: - The phloem
transports food in the form of sugar solution from leaves to all other parts of
the plant. Sugar solution can go up and down the phloem at the same time,
(14) Define transpiration.
Answer: - The loss of
water from stomata in the leaf is called transpiration.
(15) Under what condition a plant will
wilt?
Answer: - A plant will
wilt when water loss is more the water intake by it.
(16) Briefly explain photosynthesis.
Answer: - In
photosynthesis plants use carbon dioxide and water in the presence of sunlight
to produce glucose and oxygen. The word equation for photosynthesis is as
under.
(17) Name the factors necessary for
photosynthesis.
Answer: - Photosynthesis
require light, chlorophyll, carbon dioxide, water and suitable temperature.
(18) Can photosynthesis process take
place in the absence of chlorophyll?
Answer: - Photosynthesis
process cannot take place in the absence of chlorophyll.
(19) Define respiration.
Answer: - The process in
which living things get energy from their food.
(20) Describe respiration process in
plants.
Answer: - In plant cells,
glucose reacts with oxygen to form carbon dioxide, water and energy. Carbon
dioxide and water are the waste products.
(21) Where does respiration take place
in a plant?
Answer: - The respiration
takes place in the mitochondria of a plant cell.
(22) Does
photosynthesis process take place at night?
Answer: - As sunlight is
a necessary factor for photosynthesis therefore photosynthesis process stops at
night.
(23) Which gas is released by plants at
night?
Answer: - At night,
carbon dioxide gas is released.
Give detailed
answer to the following questions.
Differentiate between
taproots and fibrous roots?
Answer
Taproots: - A taproot
system has one main root called primary root that grows downward. Many smaller
roots branch out from primary root known as secondary roots. The branches of
secondary roots are called tertiary roots. Taproots are found in many plants,
trees and shrubs.
Fibrous Roots: - The
fibrous roots are thread-like structures that spread out from the base of the
stem of a plant e.g. grasses and wheat.
Answer
The part of plant that is above the
ground is called shoot system of a plant. The parts of shoot system of a plant
are stem, leaves, flowers and fruits. We will describe only stem and leaf in
detail.
Stem: -
The stem gives support to the plant. It transports substances between the roots
and aerial parts of the plant including leaves, flowers and fruits.
The
main types of stem are herbaceous stem and woody stem. Plants
with green and flexible stems are called herbaceous (e.g. daises, grass and
crops). The pictures of herbaceous plants are shown below.
The plants with hard and strong stems are
called woody plants (e.g. trees, shrubs and most vines). A woody stem is mostly
covered with a dead layer of cells called a bark. The woody plants are
shown in the following figure.
In
a stem, vascular bundles are arranged like a ring just beneath the epidermis.
The vascular bundles are strong and provide support to the plant.
The
process of photosynthesis takes place in leaves. The outer most layer of a
leave is called an epidermis. There is a water proof
covering over epidermis called cuticle. Gases move in and out through small
holes in the leaf epidermis called stomata (singular: stoma). Surrounding each
stoma is a pair of guard cells. The two guard cells work together to open and
close the stomata. Stomata open during day time and
close at night time.
Describe the transport system in a
plant.
Answer
The transport system of a plant consists
of xylem and phloem.
Xylem: - The xylem
system transport water and dissolved minerals from the roots to the leaves
through the stem. They have thick and strong walls to support the plant. Xylem
is a dead tissue. In trees new xylem is made each year forming rings in the
tree trunk. Xylem forms wood.
Phloem: - The phloem
transports food in the form of sugar solution from leaves to all parts of the
plant. Sugar solution can go up and down the phloem at the same time.
Discuss in detail the
photosynthesis process.
Answer
Photosynthesis
Leaves and other parts of the plant are
green because of chlorophyll. It is a green pigment that absorbs light energy
and is present in the chloroplast of the plant cell. It enables a plant to make
its own food by the process of photosynthesis. During photosynthesis, plants
use light energy from the Sun, carbon dioxide from the air and water from the
soil to make glucose and oxygen.
Carbon dioxide enters the leaf through
stomata and water comes from xylem to the leaf cells. The glucose produced is
transported to all parts of the plant. Cells use it to produce energy. Some of
the glucose is changed into starch and stored for future use while some glucose
is converted into other substances that make up the plant body e.g. cellulose.
Oxygen is also produced by photosynthesis. Plant cells use some of the oxygen
for respiration, extra oxygen moves out through stomata.
Photosynthesis in a
leaf
Briefly describe the
factors necessary for photosynthesis.
Answer
Photosynthesis require light,
chlorophyll, carbon dioxide, water and suitable temperature.
Starch Test for
Investigating Photosynthesis
Testing a leaf for starch is the
simplest experiment to find out if a leaf is performing photosynthesis or not.
If starch is present, leaf turns
blue black when iodine is added to it. If the leaf has not performed
photosynthesis, it will not change its colour.
Four steps of starch
test
Light
Cover a leaf from its middle
portion by a strip of black paper or aluminium foil. After a day perform the
starch test on that leaf. Which part of the leaf shows negative starch test and
why? You will observe that the portion of leaf that was covered with black
paper or aluminium foil will show negative starch test i.e. the absence of
starch.
Testing effect of light
on photosynthesis
Carbon Dioxide
Chlorophyll
Take a variegated leaf e.g. money plant
leaf. It has white patches without chlorophyll. Perform starch test on the
leaf. Which part on the leaf shows negative starch test and why? The white
patches of variegated leaf will show negative starch effect due to absence of
chlorophyll. Hence chlorophyll is another necessary factor for photosynthesis.
Water
Water is also a necessary factor for
photosynthesis. If proper amount of water is not available, the photosynthesis
process will be affected and plant will produce less food.
Suitable Temperature
The suitable temperature range for
photosynthesis is
Explain the
respiration process in plants.
Answer
Living things
get energy from their food by the process called cellular respiration. In
plants glucose reacts with oxygen to form carbon dioxide, water and energy.
Carbon dioxide and water are the waste products. This process mainly takes
place in the mitochondria.
Plant cells respire all the times, so
they need continuous supply of oxygen. During day time they make more oxygen by
photosynthesis so extra oxygen goes into air. At night, photosynthesis stops,
so plants take in oxygen and give out carbon dioxide like animals.
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