What is
global warming? What is the main reason
for global warming?
Global
warming is a dangerous phenomenon which leads to the rise in earth’s
temperature. The main reason for global warming is the increase in the level of
carbon dioxide in the atmosphere.
Why doesn’t
the level of oxygen in the atmosphere decrease?
Ans:
Plants and
animals use oxygen for respiration and carbon dioxide is expelled out. Plants
use this carbon dioxide for photosynthesis and oxygen is released. Thus the
level of oxygen is maintained in the atmosphere.
Why doesn’t the level of carbon dioxide in the atmosphere increase?
Ans:
Plants use
the carbon dioxide for photosynthesis and oxygen is released. So the level of
carbon dioxide does not increase in the atmosphere.
Which process in plants regulate the level of oxygen and carbon dioxide in the atmosphere?
Ans: Photosynthesis
List out the
factors, other than carbon dioxide that are required for photosynthesis.
Minerals and salts
Water
Sunlight
Chlorophyll
Why is the
upper part of the leaf is greener than the lower part?
Ans:
As the
function of the chlorophyll is to trap sunlight, more chlorophyll is present in
the upper area of the leaf to trap more sunlight. So the upper part of the leaf
is greener than the lower part.
Pigments in
plants
Photosynthesis takes place in chloroplast. It occurs not only
in leaves, but in regions wherever chloroplast is present. Pigments that absorb
sunlight are found in the grana of chloroplast. Chlorophyll a, chlorophyll b,
carotene and xanthophyll are the pigments present in grana. All these pigments
can absorb sunlight. However, only chlorophyll a can participate directly in
photosynthesis. All other pigments absorb light and transfer it to chlorophyll
a. Hence they are called accessory pigments.
Who
discovered cyclic chemical reactions in the dark phase?
Or
Dark phase
is known as Calvin cycle. Why?
Ans: The
cyclic chemical reactions in the dark phase were discovered by the scientist
Melvin Calvin. Hence, this phase is known as Calvin cycle.
Carbon dioxide and water to leaves
Prepare a
note on the chemical changes of glucose in plants?
Glucose is
easily soluble in water it cannot be stored in plant body. Therefore, plants
store glucose in the form of insoluble starch in leaves. Plants utilize starch
as a source of energy for life activities and to prepare substances required
for growth. Starch is later converted to sucrose and is transported through
phloem to various plant parts and stored there in different forms.
All
producers on earth do not depend on sunlight. The Sulphur bacteria seen on land
and in water are examples for this. They produce energy by breaking down
chemical compounds. This process is called chemosynthesis.
Plants
provide various nutrients required for animals. Explain.
Plants
produce glucose during photosynthesis. This glucose is converted to starch and
then to sucrose. By metabolic activities plants convert this sucrose to starch,
protein, fat, fructose and sucrose. These nutrients are stored in various parts
of the plants and it is consumed by animals.
What are the
products obtained from plants other than food and oxygen?
Beverages (
eg: coffee, tea etc.)
Latex (eg:
rubber)
Spices
(pepper, ginger, cardamom etc.)
Medicines
(neem, thulsi, adalodakam etc.)
What is the
role of oceans in the synthesis of Oxygen?
Oxygen is
essential for the existence of organisms. We know that oxygen in the atmosphere
is obtained through photosynthesis. About 70-80 percent of oxygen in the
atmosphere is contributed by algae and phytoplankton present in the sea.
Ocean gets
polluted due to various reasons. Find its reasons and prepare a short note.
Sewage
Toxic chemicals from industries
Chemical fertilizers and pesticides from agricultural land
Other
pollutants reached ocean as land runoff
Large scale oil
spills
Ocean mining
Littering
Write a
short note on the importance of plants for the sustenance of biosphere?
The service
rendered by plants for the sustenance of the living world is unique. Plants
serve as the cheapest, effective and natural means for the purification of air.
By absorbing carbon dioxide from the atmosphere and releasing oxygen, plants
provide invaluable service to the living world. Plants also have a major role
in the mitigation of natural disasters.
Cite some
examples for the mitigation of natural disasters by plants?
Mangrove
forests help in controlling Tsunami to some extend. Bamboo forests, reed,
vetiver, lemongrass etc. protect the river banks from collapsing during flood.
Trees and bushes in mountains and hills prevent soil erosion and landslide.
Nature
conservation is very important. Explain.
Nature
conservation should become part and parcel of everyone's life. Nature should be
used wisely and preserved for the generations to come. Green plants are the
protectors of biosphere. Hence for the conservation of nature, nurturing of
plants should be considered as one's prime responsibility.
Let us assess
1. Which of
the pigments given below participate directly in photosynthesis?
¢ A.
Chlorophyll a
¢ B.
Chlorophyll b
¢ C.
Xanthophyll
¢ D. Carotene
Ans: A.
Chlorophyll a
2. Glucose
formed as a result of photosynthesis gets stored in different parts of the
plant in different forms through metabolic activities. Based on this, complete
the table given below.
3)Diagram
showing the structure of chloroplast is given below. Redraw the diagram and
label its important parts.
Describe the
structure of chloroplast.
The
chloroplast is an organelle with a double layered membrane. The fluid part of
the chloroplast is the Stroma. The membranous sacs arranged one above other is
the grana. Pigments that can absorb sunlight are present in grana.
What is the
function of accessory pigments?
Ans:
Chlorophyll
b, Carotene, Xanthophyll are accessory pigments. They are seen in the grana
they can absorb light and transfer it to chlorophyll a.
Correct the
statements given below by replacing the underlined words alone, if found
incorrect.
a. Oxygen is
formed during photosynthesis by the splitting of carbon dioxide.
b. The dark
phase of photosynthesis takes place in the stroma.
c. Glucose
is transported through the phloem tube to various parts of the plant.
Ans:
a.Oxygen is
formed during photosynthesis by the splitting of water
b. The dark
phase of photosynthesis takes place in the stroma.
c. Sucrose
is transported through the phloem tube to various parts of the plant.
Plants are
the lungs of earth. Assess the relevance of this statement and prepare notes.
Ans:
Plants serve
as the cheapest, effective and natural means for the purification of air, by
absorbing carbon dioxide from the atmosphere and releasing oxygen. It is
estimated that plants give out approximately 118 kg of oxygen when they use one
ton carbon dioxide. As the plant cover on the earth decreases, this recycling
mechanism stops and the air pollution become severe. That is why the plants are
called the lungs of the earth.
What are the
causes of global warming?
Ans:
The main
reason for global warming is the increase in the level of carbon dioxide in the
atmosphere. Carbon dioxide level increases due to deforestation, atmospheric
pollution, burning of fossil fuels etc.
Complete the
word relations
Light
reaction : grana
Dark
reaction : ………
Green plants
: land
…………….....:
ocean
Take the odd
one out give reason for your answer.
Carotene,
Xanthophyll, chlorophyll a, chlorophyll b
Ans:
Chlorophyll a
Reason:
others are accessory pigments
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