Transcript Why are plants producers?

Producers
Examples of plants
Why are plants producers?
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Because only plants can combine
light energy from the sun with raw
materials from the environment
e.g. water, air to make food
molecules.
Food has chemical potential
energy and herbivores...etc are
able to break food down and take
in energy
Plants are Food factories
• Plants undergo photosynthesis, (making
food using light).
Photo = light; synthesis = making.
• Note:
1.Oxygen is used for respiration
2.Carbon dioxide is used for
photosynthesis
3.It only occurs during the day when light is
available.
Plants
• All organisms need food to
survive, food provides
e_______.
• Plants are multicellular
organisms. They contain a
green substance called
Chlorophyll and can make
food called Carbohydrates
– sugar and starch.
Parts of plants
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Roots; root hairs
Stem; Xylem and phloem
Petiole
Leaf; Stomata, cuticle
Seed
Flowers
Picture of a plant
How does photosynthesis work?
1. The process occurs inside the leaves.
2. Water, Carbon dioxide gas and sunlight
rays are needed for photosynthesis to
occur.
3. Glucose sugar, oxygen gas are the
products.
Photosynthesis equation:
photosynthesis
CO2 + H2O + Sunlight  Glucose sugar + O2
The rate of photosynthesis
• Depends on the abundance of reactants. For
example: light intensity , CO2 and water
concentration,.
• However all reactions are faster in warmer
rather than colder conditions.
• We can scientifically measure the rate by
measuring the growth in size of plants or by
the production of oxygen.
Quiz
1. Why are plants food factories?(1m)
2. Name all substances needed for plants to
produce food and all the products? (6m)
3. At day time, what gas(es) do plants produce?
Through what process(es)? (2m)
4. At night time what gas(es) do plants produce?
Through what process(es)? (2m)
5. What is the green substances in the leaves ?
(1m)
6. What does Synthesis mean? (1m)
7. What tube does plants use to transport food?
(1m)
Cross section of a leaf
Stomata
• pores allow gas exchange and control
water loss.
Structure and Functions of leaves
• Cuticles: A waxy layer which helps to reduce water loss.
• Upper epidermis: outer cell layer
• Spongy cells: contain fewer chloroplasts because light
is weaker, cells are well spaced out allowing gases to
circulate.
• Guard cells: control the size of the stomata pores which
let gases in or out.
• Lower epidermis: bottom cell layer.
• Veins: have xylem tubes ( water from roots to the whole
plant) and phloem tubes ( food from leaves to the whole
plant)
• Palisade layer cells: have lots of chlorophyll for
photosynthesis.
Adaptations of plants
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Plants need the following things to survive:
minerals
water
sunlight
warmth
air
• They develop special features
to survive in different
environments:
3 types of adaptations:
1.Structural adaptation:
visible features; e.g. thin needle like
leaves.
2.Functional(physiological)
adaptation:
Life processes, e.g. photosynthesis,
respiration.
3. Behavioural adaptation:
Behaviours that plants exhibits, e.g.
plants growing towards light.
Structural adaptations of leaves:
External adaptation
1.Wide blade:
captures maximum sunlight.
2.Thin leaf:
allows maximum light penetration
3.Vein network:
supports leaf, transport water and sugar and minerals
4.Green colour:
Chlorophyll to trap sunlight.
5.Pores in leaf:
allow gas movement through the leaf
6.Waxy surface:
prevent excessive water loss
7.Strong petiole:
holds leaf up to sunlight
Internal adaptations:
1.Epidermis layer cells:
Protect the leaf and reduce water loss by making
the waxy surface.
2.Palisade layer cells:
Contain lots of chlorophyll
3.Spongy layer cells:
Well spaced to maximize light and gas absorption
4.Veins:
Bring water from the roots and phloem tubes,
carry sugars around.
5.Guard cells:
Control the size of the stomata pores.
Transpiration
• Loss of water from the leaves of a plant by
evaporation.
• Water first enters plants through the roots
(root hairs). Water is absorbed into the root
by osmosis.
• Water travels up the plant to the leaves
through (small microscopic/ capillary tubes)
by capillary action.
• Eventually water reaches the stomata then
escape through evaporation.
• Xylem experience a loss in pressure, so water
is sucked up the xylem through suction
pressure.
Transpiration increases when:
1. The leaf stomata
are open
2. The air is dry
3. It is warm
4. It is windy
5. The leaves have a
large surface area
Osmosis
• Osmosis is the process by which water is absorbed into
roots.
• The root hair’s surface is a semi permeable membrane.
• Water always moves from a higher concentration to a
lower concentration.
• The larger the concentration difference, the faster the
movement (diffusion) of water.
• E.g. A dry towel absorbs water faster then a wet towel.
• Water is diffused into the root from the soil if the water
concentration is higher/lower in the soil.
Absorption of water by plants
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A plant’s root system
maximizes water
uptake in 2 ways:
1. Taproot: grows
downwards to access
water deep in the
ground.
2. Lateral roots: sideway
roots which access
water closer to the
surface.
Plant classification
Angiosperm
Flower bearing plants
Gymnosperm
• Cone bearing plants
Angiosperms, flowering plants, are
divided into two groups:
• monocots
•dicots.
• Dicots
Plant reproduction
• Plants can reproduce asexually or
sexually.
• Asexual reproduction
• as runners (strawberries) or side
branches (busy lizzy).
• as potatoes, storage organs develop
underground which grow into new
plants. This is called vegetative
propagation and examples include
tubers, bulbs and rhizomes.
• cuttings or grafts, which can grow
into a new plant.
Sexual reproduction
• Plants can also reproduce by sexual
reproduction. The offspring have the
genes from two parents - their genes are
different, so the offspring will not be
identical. There is variety in the species.
Flower parts
• Petals- attracts insects
• Stamen- male sex organ
• Anther – produce pollen
grains
• Filaments- rises the
anther
• Carpel – female sex
organ
• Sepal – protects the
flower when it is a bud
Flower