– Plants with green and tender stems almost no
branches. E.g: Tomato – Herb
– Branches near the base, thin but hard stem. E.g:
Thick, brown stems. Tall with branches near the top. Mango
– Tree. Branchy part of the tree above the stem is called
crown. Crowns of tall trees form a roof like structure
called Canopy. Crowns of smaller trees form a
lower layer called Under-storey.
with weak stems that spread on ground or take support of
other structures. [Money plants, beanstalk, gourd, grape
Parts of a Plant
– conducts water and minerals.
part of a leaf by which it is attached to the stem - petiole.
broad, green part of the leaf - lamina
– lines present on the leaf. Thick line in middle is
of veins – venation is of two types reticulate –
net like or parallel.
– Leaves releasing water in the form of water vapor.
The evaporation of water from leaves creates a suction
that pulls water from roots to greater height. It also
cools the plant.
is the tissue in plants for transportation of water
and minerals. Food is transported by a second tissue
called phloem. Xylem is made of trachids, vessels,
parenchyma and fibers. Unidirectional movement is
is also a complex permanent tissue like xylem and
consists of sieve tubes, companion cells, parenchyma and
fibers. Transport food in both directions.
– Leaves prepare food using carbon dioxide and water
and food produced is stored in form of starch. Oxygen is
released in this process. Amount of oxygen released during
photosynthesis is much higher than the CO2 that is
released during night time.
following things occur in photosynthesis, absorption of
light energy by chlorophyll, conversion of light energy
into chemical energy and splitting of water molecules into
hydrogen and oxygen. Reduction of CO2 into carbohydrates.
These steps need not occur immediately.
take in CO2 from atmosphere through pores present on
surface called stomata; these are surrounded by
guard cells. Leaves have a green pigment called
chlorophyll that captures energy from the sun and uses it
to synthesize food using water and CO2. Roots also take in
air from the soil.
Types of food production in Plants
is a parasitic plant that takes nutrition from
other host plants. Pitcher plant is insectivorous
plant but it also carries out photosynthesis. These plant
doesn’t get sufficient nutrition from the soil.
like yeast, Mushrooms are saprotrophs that feed
on decaying matter.
relationship: Some organisms live together and share food
and nutrients. [Lichens – Algae and fungus live together.
Algae provide food by photosynthesis and fungi provide
water, nutrients and shelter. They are good indicators
of pollution as they don’t grow in polluted areas. ]
a bacteria converts atmospheric nitrogen into
soluble form; this is absorbed by the leguminous plants
that in turn provide it shelter and food. Thus nitrogenous
fertilizers are not needed for leguminous plants. ]
fungi – Phosphorous fixing fungi lives in the roots
of higher plants.
– nitrogen fixer bacteria for non leguminous plants.
green algae, nostoc, azotobacter and Lightning
are also nitrogen fixers. Ammonia is converted to
nitrites by nitro somas and nitrococcus. This is
converted to nitrate by nitrobacteria.
poisoning of ground water causes methaemoglobina [blue
Roots and their features
absorb water and nutrients from soil by a process called
osmosis. They anchor the plant to the soil. Root hairs
increase surface area for absorption.
types are tapped root [a main root and lateral
root] or fibrous roots [hair like roots]. Some
plants like banyan, grass roots arise from parts other
than radicle called adventitious roots.
with tap roots have reticulate venation and with fibrous
roots have parallel venation system.
roots - carrot, radish, sweet potato, turnip and tapioca.
stems, leaves are vegetative parts of plants and flowers
are reproductive parts of plants.
types of tissues in plants – permanent [non-growing]
and meristematic [growing]. Depending on their
location they are apical, intercalary or lateral.
Initially meristems grow cells same as themselves but as
these cells grow and mature they get differentiated into
components of other tissues. Meristem cells have dense
cytoplasm, no vacuoles, thin cell walls and large nuclei.
tissue is of multiple types like
– these are living tissues which store food and
provide support to plants. They may contain chlorophyll
and then it’s called chlorenchyma. In floating plants it
has air in the intercellular space and is responsible for
buoyancy and called aerenchyma.
are living tissue which provides mechanical support
to plant and also flexibility without breaking.
is dead tissue but hard and no intercellular space.
It provides mechanical support to plant. Cell walls are
thick due to lignin. Epidermis is the single, continuous
layer of cells that covers entire plant body. It has pores
called stomata at certain in points that allow gaseous
exchange. Epidermis is thicker in plants in deserts to
prevent water loss.
These are present in plant tissue in large number; some
are obtained from water [H, O], from air [C] and rest from
soil [N, P, K, Ca, Mg, and S]. Useful as components of
biomolecules, activate/inhibit enzymes, components of
energy related substance, affect osmotic potential of
Needed in small amounts. These include iron, manganese,
copper, molybdenum, zinc, boron, chlorine and nickel.
of N, K, and Mg are visible in senescent leaves as
biomolecules with these elements are broken down to
mobilize younger leaves. Boron and calcium deficiency
leads to death of meristem, buds and tips. Phosphorous
deficiency [blue leaves] and Fe, Mn, Mg, N deficiency
manures – cover crop that is planted on the field
and ploughed under while its green. This is done to
improve nutrients in the soil.