2 – PLANTS : STRUCTURE
AND FUNCTION
Q. 1. Give examples of three plants that have
:
Answers:
(1) Spiny fruits - (1) Jack
fruit (2) Datura (3) Castor
(2) Spiny stem - (1) Cactus
(2) Silk Floss tree (3) Silk cotton tree
(3) Red flowers - (1)
Hibiscus (2) Erythrina (Indian coral tree)
(3) Flame of the forest
(4) Yellow flowers - (1)
Golden trumpet tree (2) Golden shower the
(3) Yellow Canna
(5) Leaves which close at night - (1) Amla
(2) Gulmohur (3) Rain tree
(6) Single-seeded fruits - (1) Mango (2)
Berries (3) Cashew
(7) Many-seeded fruits - (1) Guava (2) Jack
fruit (3) Water-melon
Q 2. What are the
similarities and differences between?
(1) Jowar and
Moong:
Ans. Similarities :
Both are food stuffs.
Jowar
Moong
1. Jowar
is a monocotyledonous plant. 1.
Moong is a dicotyledonous plant.
2. Jowar
seed has single cotyledon.
2. Moong seed has two cotyledons.
3. Jowar
grain is full of carbohydrates. 3. Moong seed is full of proteins.
4. Jowar
grains are seen in cobs.
4. Moong are present in legumes.
(2) Onion and Coriander :
Ans. Similarities : Both are consumed in the
form of salads. They are used plementary food stuffs in cooking and also for
garnishing.
Onion Coriander
1. Onion is a monocotyledonous plant. 1. Coriander is dicotyledonous plant.
2.Onion is grown from seed or its bulb. 2. Coriander is grown from its seeds.
3. The edible onion is actually a modified 3. Coriander are leaves
leaf.
(3) Leaves of banana and mango:
Ans.
Similarities : Both the leaves have religious, importance and sacred
Leaves of banana Leaves
of mango
1. Banana is a monocotyledonous plant. 1. Mango is a dicotyledonous plant
2.
Banana leaf has parallel venation 2. Mango leaf has reticulate
venation
(4) Coconut tree and Jowar stalk plant :
Ans. Similarities : Both are monocotyledonous
plants that yield food stuffs.
Coconut tree Jowar
stalk plant
1. Coconut tree is strong and very tall. 1. Jowar stalk plant is dwarf and
weak can be uprooted with ease.
2. Coconut plant is perennial 2. Jowar plant dies
soon after the cob
is grown
3. Coconut tree has adventitious roots. 3. Jowar has adventitious and stilt
roots for additional support
Q. 3. Certain properties are mentioned below.
Find a leaf corresponding to each
property and describe those plants :
Leaves
with smooth surface, leaves with rough
surface, fleshy leaf, spines on leaf.
(1) Leaves with smooth surface : Banana leaf
Ans. Banana plant has smooth leaves which are
used as feeding plate in many states of India. The banana plant is the largest
herbaceous flowering plant. It grows from a structure known as corm. It looks
like a tall and sturdy tree but it's trunk is actually a 'false stem or
pseudostem. The leaves of banana plants are composed of a petiole and a lamina.
The base of the petiole widens to form a sheath; the tightly packed sheaths
make up the pseudostem which supports the plant. Each pseudostem normally
produces a single inflorescence, also known as the 'banana heart', locally
known as kelphul. Bananas grow from a kelphul.
(2) Leaves with rough surface : Parijataka
leaf (Night flowering Jasmine)
Ans. Parijataka tree has rough leaves. It is
dwarf tree growing to about 10 metres that bears beautiful white flowers with
red peduncles. The flowers bloom at night and in the morning one can notice a
carpet of parijatka flowers under the tree. The rough leaves of this tree are
extremely medicinal. Many Ayurvedic and homeopathic drugs are prepared from
these leaves. There are many mythical tales about this tree in Indian
mythological literature However, in English this tree is called 'tree of
sorrow' because the flowers cannot sustain the sunlight and dry up soon with a
daybreak.
(3) Fleshy leaf: Eicchornia leaf (Water hyacinth)
Ans. The leaves of Eicchornia or water
hyacinth are fleshy. Water hyacinth grows in water as a submerged plant. The
stem of the plant is also swollen and green. It bears bluish violet flowers
throughout the year. A single Eicchornia plant produces more than 3000 seeds in
one year. The plant grows very rapidly and it needs to be controlled. Otherwise
it causes eutrophication and depletes the oxygen in the water body causing the
death of fish. Eicchornia thus affects biodiversity and environment of water
bodies.
(4) Spines on leaf : Pandanus leaf (Kevda)
Ans. The leaf
blade or lamina of Pandanus bears spines. The Pandanus is locally known as
Kevda. The plant of kevda grows to about 1 metre length. The stem is strong and
is of medium size. The leaves form a crown like structure at
the top of the tree. These leaves are fragrant. They are used for decorating.
Male and female flower is borne on separate plants.
Q. 4. Explain the following images in your
own words:
Ans. (1) Figure 'A' is of monocotyledonus
seed. It is a grain of Maize Figure 'B’ is of
Dicotyledonous seed. It is a bean seed,
(2)
Each figure show entire seed/grain and a longitudinal section of the same.
(3) In
figure A: The radicle and plumule is seen inside the covering surrounded by
starchy
substance. There is a single cotyledon.
(4) In
figure B: The radicle and plumule are seen on the upper side of cotyledon. There
are two cotyledons.
Q 5 Describe the functions of various parts
of a plant.
Ans. (1) Various parts of the plant are as
follows: Root, stem, leaves, flower and fruit.
(2) Functions of the roots : (a) anchoring
and supporting the plant (b) absorption of water and minerals (c) Some roots
show some modifications for performing additional functions. e.g., Aerial roots
absorb moisture from air, stilt-roots give additional support runners-help in
vegetative propagation, breathing roots (pneumatophores). Breathe for plants,
some underground roots store food materials etc.
(3) Functions of the stems : (a) To hold all
the branches of the plant (b) To perform function of photosynthesis as in
cactus (c) To transport water absorbed by the roots to all the parts of a plant
and to transport food prepared by the leaves to various plant parts. (d) Modified
stems perform functions such as food storage, reproduction, support etc.
(4) Functions of the leaves : (a) Production
of food by performing photosynthesis (b) Transpiration, i.e. giving out excess
of water (c) Modified leaves perform addition functions such as reproduction,
food storage, support etc.
(5) Functions of
flowers : Reproduction
(6) Functions of
fruits : Protection of seeds and storage of food materials.
Q. 6.Observe any one flower and its various
parts and describe it in your own words.
Ans. Flower
chosen in Hibiscus.
(1) Hibiscus flower has a pedicel.
(2) All the whorls are arranged over the
thalamus.
(3) Four important floral whorls are seen
clearly. These are :
(A) Calyx : Calyx has five sepals. This part
is green
(B) Corolla : Corolla is made up of five
petals which are big and bright red in
colour. The petals are free from each other.
(C) Androecium : This part is a male part of
the flower. The stamen looks like a
long tube. At the end of this tube are seen
anthers. Anthers are attached to this tube by tiny filaments. Pollen grains are
seen on the anthers. Some of the pollen grains stuck up to the hands.
(D) Gynoecium : This is a female part of the
flower. At the end of the flower near
thalamus the gynoecium is present. After
taking the vertical section of the flower by a blade, the ovules are seen
inside the ovary. The style starts the ovary and ends in five stigma at the top
of the flower. The gynoecium thus made up of five carpels.
