TC1CROPSCI101 Plant and function_PART-2.pdf

NATURE AND COMPOSITION OF CROP PLANTS
I. The Plant Cells (Parts and Functions)
II. The Anatomical Regions of the Plant Body
III.The Plant Organs

Cell- smallest structure in the universe capable of growth and
reproduction.
- basic unit of every living organism
- an autonomous living system capable of independent
existence and propagation
- Fundamental morphological unit of plant body

I. Difference between plant and animal cells
Plant Cell Animal Cell
Has chloroplast for photosynthesis NO chloroplast
Has Cell Wall NO Cell Wall
Has large Central Vacuole Has smaller vacuole
NO centrioles and lysosomes Has centrioles and lysosomes

I. Plant Cell has three (3) main components
A. Cell wall
B. Cytoplasm
C. Nucleus

A. Cell Wall
-Povides mechanical protection and rigidity to the plant cell
-Consist of cellulose that overcome pressure due to its elastic
property.
-Composed of cellulose, hemicellulose, pectic substances,
organic and inorganic substance, lignin, enzymes, protein and
water

Three Layers of Cell Wall
1. Middle Lamella- where pectin cements adjacent cells
together
2. Primary Wall-thin, not rigid, stretched as the cell grows,
layer formed before and during growth of the plant cell,
consist of cellulose microfibril, have primary pit fields,
thin areas that tranversed by numerous protoplasmic
strands called plasmodesmata.
3. Secondary wall- rigid, thick, formed after cell completes
growth.

B. Cytoplasm
-all living matter of the cell apart from the nucleus
-Gel-like material or fluid in which the cell’s organelles and
internal membrane system are suspended
-distribute substances absorbed from outside and released by
the nucleus and other organelles (through cytoplasmic
streaming/cyclosis-flowing movement of cytoplasm)

Cytoplasm consist of the following:
1. Plasmalemma/plasma membrane
2. Endoplasmic Reticulum
3. Golgi Apparatus
4. Mitochondria
5. Plastids
6. Microbodies
7. Cytoskeleton
8. Ribosomes
9. Vacuoles

1. Plasmalemma/plasma membrane- has selective
permeability
Functions:
-allows some substances to cross easily and completely block
substances
-accumulates the ions or the molecules in the cytosol through
the action of transport proteins that consumes metabolic
energy
-coordinates the formation of cell wall microfibrils

2. Endoplasmic Reticulum- flattened disks or tubular sacs
Types:
A. Rough Endoplasmic Reticulum (with numerous
ribosomes)
-involves in the synthesis of lipids
B. Soft Endoplasmic Reticulum (lack ribosomes)
-involved in the synthesis of membrane proteins and
secretory proteins

3. Golgi Apparatus- collective term for all dictyosomes
(consist of stack of flattened hollow disks called cisternae) or
golgi bodies
Functions:
-involved in the synthesis of polysaccharides and glucose
units for cell wall formation.
-secretes protein and carbohydrates from the cell to the
exterior part (ex. nectar coming out from the flower)

4. Mitochondria- (powerhouse) small cylindrical organelles
enclosed by two-unit membranes
A. Outer Membrane- permeable for smaller particles,
contains the respiratory chain component and enzymes for
the synthesis of ATP.
B. Inner Membrane- impermeable and folded into
numerous cristae.
Functions:
-site of respiration (energy source for plants body
maintenance, growth and development)

5. Plastids- differentiated into system of membrane (2 units)
and ground substance, the stroma.
TYPES:
a. Chloroplast
Function: site of photosynthesis; involved in amino and fatty
acids synthesis; provides space for temporary storage of
starch.
b. Chromoplast- responsible for the yellow, orange or red
colors of many flowers and other parts of the plants
Functions: Attracts insects and other animals

c. Leucoplasts-nonpigmented plastids but once exposed to
light, it may develop into chloroplasts
• Amyloplast-starch
• Proteinplast-protein
• Elaeioplast- fats and oils

6. Microbodies-spherical organelles bounded only by one
membrane, about 0.5 to 1.5 micrometer in diameter.
Functions:
Peroxisomes (term to some microbodies) play an important
role in glycolytic and metabolism associated with
photorespiration.
Lyoxysomes (other microbodies) contain enzymes needed for
the conversion of fats into carbohydrates during germination
in many seeds.

7. Cytoskeleton- an organized cytosol into a three
dimensional network of fibrous protein.
- each is made of sub units of the protein called tubulin
Types:
i. Microtubules- long, thin, cylindrical structures about 24 mm
in diameter and of varying lengths.
Functions:
a. involve in the orderly growth of the cell wall, especially the
control of cellulose microfibrils alignment.
b. Formation of the cell plate (initial partition of dividing cell)
c. Involve in the movement of flagella and celia in which
microtubules are important components of it.

7. Cytoskeleton- an organized cytosol into a three
dimensional network of fibrous protein.
- each is made of sub units of the protein called tubulin
Types:
ii. Microfilaments- consist of two actin chain (similar to that of
muscle tissue) that maintains in helical fashion.

7. Ribosomes- small particles about 17-23 nm in diameter
containing an equal polyribosomes or polysomes.
Functions:
-intercellular structure made of both RNA and protein, and it
is the site of protein synthesis in the cell

7. Vacuoles-enclosed by a unit membrane called tonoplast
-dumping house of the cell, contains water and other
substances.
Functions:
-absorb toxic products
-stores various metabolites
-breakdown macromolecules and the recycling of their
components with in the cell.

C. Nucleus - contain the genetic information indispensable
for the cells life and metabolic function.
Functions:
-controls the activities of the cell by determining which
protein molecules are produced and when they are produced.
-stores the genetic information

The Anatomical Regions of Plant
-most plants are made up of four basic parts:
1.leaves-for photosynthesis
2.stems-for support
3. roots-for absorption of water and minerals
4. flowers- which later become fruit or seeds
(for reproduction)

Parts of the Plant: Leaves
-food factory of the plant, producing all food that is used by
the plant and stored for later use by the plant or by animals.
-site of Photosynthesis.

-(1) Leaf base; (2) petiole and 3) Lamina or leaf blade. The
Blade, or lamina, is the broad, flat part of the leaf.
Photosynthesis occurs in the blade, which has many green
food-making cells.

-Leaf base
This part of the leaf is attached to the stem or the branch. In some plants, a
leaf-like growth arises from the side of the leaf base. These are stipules. This
type of stipule is noticed at the leaf base of a pea.
Stipules
The leaf-base often bears a pair of lateral appendages or outgrowths called
stipules. Some stipules, such as those of willows and definite cherry trees,
create substances that avert insects from attacking the developing leaf.

-Petiole
The Petiole is the stem like part of the leaf that joins the blade to the stem. This is the stalk
which might fix the leaf to the stem; some leaves connect directly and don’t have petioles.
Within a petiole are tiny tubes that connect with the veins in the blade. The petiole has little
tubes, which attach the veins on the leaf blade to the stem. Some of the tubes hold water into
the leaf. The cylinder-like part of a leaf is petiole. It connects the leaf base and
lamina. Leaves attached via a petiole are called ‘petiolate’, leaves which connect directly are
called ’sessile’.

-Lamina or Leaf blade
This is the major part of the leaf, also called the ‘blade’. It’s usually large and flat. The flat and
extended green part next to the petiole is lamina. It is in this layer that photosynthesis occurs. The vein
that runs from the tip of the petiole to the other end of the leaf blade is mid vein. From the midvein
originates veins and vein inlets. The edge of the lamina is the leaf margin. The cells of the lamina,
mainly those near the surface of the leaf, contain a high volume of chloroplasts, which carry out
photosynthesis. Photosynthesis occurs in the blade, which has many green food-making cells.
Leaf-blades differ from one another in several ways: (1) the types of edges, (2) the patterns of the
veins, and (3) the number of blades per leaf. The lamina or leaf blade is the mainly conspicuous and
essential part of the leaf. It is characterized by green color, thinness, and smoothness.
Veins
Smaller veins turn off from the midrib to make sure that the transportation organism of the plant
extends to all parts of the leaf. The sections between the leaf veins are known as ‘inter-veinal’ areas.

Parts of the Plant: Stems
Functions:
• The stems in plants have many functions.
• The stem transports water and dissolved mineral salts from the
soil to the leaves.
• After the food has been made in the leaves, it moves downwards
through different tubes in the stem to the roots for storage.
• The other main function of the stem is to support the leaves so
that they can receive plenty of sunlight and air.

Parts of the Stem:
(i) Node – The place from where the lanes grow is the node. A
node is a point on the stem from which leaves or buds arise.
(ii) Internode – The space between the two nodes is the internode.
The inter-node helps the plant to grow and keeps it erect. No roots,
leaves or branches grow from the internode.

Parts of the Stem:
(iii) Bud – A bud is an embryonic stem that has the potential for
further plant growth. The angle formed by the stem and the leaf is
called axil of a leaf. It may develop into a leaf, flower, or both.
Generally, buds grow in the axil. However, it may also grow at the
apex of the stem. The auxiliary bud grows in the axil and apical
bud grows in the apical position of the stem or branch. Such buds
are called leaf buds, flower buds, and mixed buds, respectively. As
a result of injury, adventitious buds may be formed also in the
internode of the stems, in leaves, or roots. The “eyes” of the potato
tuber are buds.

Parts of the Stem:
Vascular tissues
Phloem- carries food to roots
Xylem- carries water and minerals upward

Parts of the Plant: Roots
Functions:
-for anchorage and absorption
The root is covered at the apex by a thimble-like structure called the root
cap. It protects the tender apex of the root as it makes its way through the
soil. A few millimeters above the root cap is the region of meristematic
activity. The cells of this region are very small, thin-walled and dense
protoplasm. They divide repeatedly. The cells proximal to this region undergo
rapid elongation and enlargement and are responsible for the growth of the
root in length.
This region is called the region of elongation. The cells of the elongation
zone gradually differentiate and mature. Hence, this zone, proximal to the
region of elongation, is called the region of maturation. From this region
some of the epidermal cells form very fine and delicate, thread-like structures
called root hairs. These root hairs absorb water and minerals from the soil.

Parts of the Plant: Roots
(iii) Region of elongation
This is placed next to the meristematic region, in which, the cells elongate
and expand to make the root produce in length. This zone is accountable for
the development in length of the root. Here the cells enlarge to make the root
grow in length. The length is about 4-8 mm. These cells slowly differentiate
and grown-up.
(iv) Region of maturation
This is subsequently to the area of elongation, in which, the cells grown-up
and set apart into diverse tissues constituting. The zone of maturation is
proximal to the zone of elongation. Root hair to absorb water and nutrients
from the soil. It also gives rise to lateral roots.

Parts of the Plant: Flower
-Attracts insect and animals
-for reproduction (Pollination)

1. Pistil
The pistil is considered the “female” part of a flower because it produces
seeds. Its purpose is reproduction. It’s made up of the following parts:
Stigma
The stigma is the upper part of the pistil. It receives the pollen to affect
reproduction.
Style
The style is the long part of the pistil. It provides a place for the pollen tube to
grow. It also acts as a barrier for bad pollen.
Pollen Tube
The pollen tube is a part of the pistil that is located inside of the style. It
enables the pollen to go from the stigma through the style to the ovary.

Ovary
The ovary is the enlarged part of the pistil located at the end of the style.
The ovary is designed to protect the ovules. It’s the job of the ovules to
fertilize the pollen to grow it into a seed.
In flowering plants that produce fruit, the ovary usually develops into the
fleshy fruit that surrounds the inner seed.
Ovule
The ovule is located inside of the ovary. Basically, these are the flower’s
eggs.
The pollen will travel from the stigma through the style to the ovary. Once in
the ovary, the pollen will then fertilize the ovules.
This fertilization ensures the ovule will eventually develop into a seed. In
some plants, only a seed will be grown. In other plants, a seed and a fleshy
fruit will be grown simultaneously.

2. Petal
The petal is the colored part of the flower that gives it a unique shape.
Petals are often brightly colored to attract insects, birds, bees, and other
animals. In this way, the petals aid with the pollination of the plant.
3. Stamen
The stamen is considered the “male” part of a flower because it produces the
pollen. Its job is reproduction.
Anther
The anther is located on the end of the filament. It’s usually fairly compact
and is where the pollen is created.
Filament
The filament is the long narrow part of the stamen that supports the anther. It
connects the anther to the rest of the flower.

Parts of the Plant: Fruits
The fruit is a characteristic feature of the flowering plants. It
is a mature or ripened ovary, developed after fertilization. If a
fruit is formed without fertilization of the ovary, it is called a
parthenocarpic fruit. Generally, the fruit consists of a wall or
pericarp and seeds. The pericarp may be dry or fleshy. When
pericarp is thick and fleshy, it is differentiated into the outer
epicarp, the middle mesocarp and the inner endocarp.

-The seed contains embryo and cotyledon (endosperm) which
are protected with a seed coat.
The seed grows under favorable condition (moisture,
temperature, oxygen and sometimes light).
-From the embryo, the root and shoot develop.
-The seedling grows due to cell division in the meristematic
tissues.

TC1CROPSCI101 Plant and function_PART-2.pdf

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