all about plants summary

8/3/2019 All About Plants Summary

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LEAF

Leaf is the place where photosynthesis or the food making process in green plants

occurs. In general, leaf morphology is thin flat, and green because it consists ofgreen pigment (chlorophyll)

Functions of Leaf

Places of PhotosynthesisThe main function of a Leaf is as the place to make food through the process of

photosynthesis. Photosynthesis in Leaf happens at thePalisade mesophyllwhich

contains lots of chlorophyll

Photosynthesis reaction:

Place for Gas ExchangeHappens through stomata which can be found on the surface of the leaf. Gas

exchange happens during photosynthesis, respiration, and transpiration. Duringphotosynthesis, gas exchange happens; Carbon dioxide enters oxygen exit during

respiration gas exchange also occurs ; carbon dioxide exit and oxygen enter.

During transpiration, the excess water as result of transportation is expelled in

the form of vapor through stomata

The Structure of Leaf

A leaf is supported by a stalk. The stalk is connected to vascular tissue. The

vascular tissues that have many branches form the veins.


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External Structure Internal Structure

a. External structureCommonly leaf have a flat an broad shape with a green colour. The green colour

caused by chlorophyll which is located in chloroplast. Leaf has various venation

patterns and edge of leaf :

a. Pinnately netted (menyirip) ex: Mangob. Palmately netted (menjari) ex: Papaya, Singkongc. Parallel venation (sejajar) ex: Pandan, Coconutd. Smooth edge (pinggiran daun halus) ex: Orange, Mangoe. Serrate edge (pinggiran daun bergerigi) ex: Rose


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Smooth Edge Serrate Edge

b.

Internal structure

The internal structure of a leaf consists of the epidermis, palisade mesophyll, and

spongy mesophyll.

Internal Structure

1. EpidermisEpidermis is a single layer on the upper and the lower surface of the leaf. The

epidermis is covered by a thin waxy layer called a cuticle. A cuticle makes the

epidermis waterproof so it prevents loss of water.


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Stomata are found in the epidermis. Stomata functions as the place of gas

exchange. Dicot plants only have stomata on the lower epidermis. Monocot

plants have stomata on the upper and lower epidermis.

2. Palisade mesophyll

Under the upper epidermis, there is a palisade mesophyll. The palisade mesophyll

consists of columnar cells which are stacked closely together. The palisade cells

have many chloroplasts which contain chlorophyll. In this palisade mesophyll the

process of photosynthesis occurs.

3. Spongy mesophyll

Under the palisade mesophyll is the spongy mesophyll. Cells in the spongy

mesophyll are packed loosely and are irregularly arranged. In spongy mesophyll


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there are veins which function as a vascular bundle. The veins consist of xylem

and phloem

ROOT

Rootis the organ of the plant that typically lies below the surface of the soil.

A root can also be aerial(growing below the ground) or aerating (growing up

above the ground or especially above water).

The first root that comes from a plant is called the radicle.

Functions of Root

o Absorb or take in water and minerals from the ground is called osmosiso Holdthe plant in place.


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o Store foodfor the plant.o Prevent soil erosion.o Form apassage way for water and dissolved substancesfrom the root into

the stem and also for foods from the stem down into the root.

Primary and Secondary Root

Primary Root

Secondary Root (Lateral Root)

Primary Root

The primary root is the central, first-formed, main root. The primary root

originates at germination stage from the radicle of the seed. During its

growth it branches to form the secondary roots.

Theprimary root may develop and forming into two different types of root

systems:

a) Taproot systemb) Fibrous root system Taproot System

Taproot system is when the primary root is prominent, grows downwards and has

smaller branches extending outward that are fibrous. This kind of root

system are mostly found in dicotyl plants.

Many taproots are modified to become food. (example, in the carrot)


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Fibrous Root SystemFibrous root system is kind of root system in which both primary and lateral roots

are finely divided and have similarly sized roots. This kind of root system aremostly found in monocotyl plants.

Secondary Root (Lateral Root)

Secondary root is a side branch of the primary root that is extend horizontally. Its

branching of roots also contributes to water uptake, and facilitates the extraction

of nutrients required.

Primary Root

Secondary /Lateral Root


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Difference between primary root and secondary root

Primary root grow first, they are much more thicker than the secondary roots and

they go downwards. Secondary root is grow out of the primary, they are not as

thick as the primary root and they go sidewards.

Root Structure

Root Tip

Root tip consists of:

Meristem - a region of rapid mitosis, which produces the new cells for rootgrowth (actively dividing cells).

Root cap a group of thimble-shaped cells that covers and protects themeristem from abrasion and damage as the root tip grows through the soil.

This cap has a column of cells in its interior that are meristematic

The region of Elongation. It is an area in plant roots where recentlyproduced cells grow and elongate prior to differentiation. At this time that

they are sensitive to gravity and respond with gravitropism. Gravitropism is

a turning or growth movement by a plant or fungus in response to gravity.

In this part, the newly created cells expand in their long dimension to pushthe meristem and root cap through the soil.

The Region of DifferentiationHere, it develops the differentiated tissues of the root.


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The Tissues


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Epidermis. A single layer of flattened cells at the surface. When firstformed, epidermal cells have extensions the root hairs which greatly

increase the surface area available for the uptake of water from the soil.

Cortex. A band of parenchyma cells that develops beneath the epidermis. Itstores food. Its inner surface bounded by a single layer of cells

(Endodermis)

Endodermis. The layer of tissue deep in vascular plant, it is the inner mostlayers of the cortex with no intercellular spaces. Its function is to regulates

the water flow.

Cambium - In older parts of the root, another meristem forms between thexylem and phloem. Mitosis in the cambium produces new secondary

xylem to the inside and secondary phloem to the outside.

Stele The central part of the root containing the tissues derived from theprocambium. These include vascular tissues, in some cases grand tissue

(pith) and a pericycle. Its function is to transport water and minerals.

Pericycle the outer boundary of the stele. Secondary roots branch from it. Xylem the main part of the tree trunk made up of tiny tubes which

transport water and minerals from the roots up the trunk and branches to

the leaves.

Phloem - a protective layer made up of tiny tubes that transport the sugarsfrom the leaves to the rest of the tree.


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Root hair A thin hair-like outgrowth of an epidermal cell of a plant root that

absorbs water and minerals from the soil.

Monocot Root


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The Difference of Monocot and Dicot Roots :

Dicots have Cambium Monocots have no Cambium

STEM

Stem is the part of the plant that supports the body of the plant.

Function of Stem


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Stem is the place in which water and minerals pass trough from the roots to the

leaves (xylem) and also the place in which the results of photosynthesis(nutrients)

pass through from the leaves to other parts of the plant (phloem).

Stem Structure

The external structure of the stem in high plant classification is differentiate into

woody plants and herbaceous plants, while the internal structure consist of

epidermis, cortex, endodermis, stele and cambium (in dicots plant).

a. External Structureo Woody Plants

Woody plants have certain firm and thick characteristic. They have

lenticels in certain parts. Lenticels connected with the inner part of as

a place for gas exchange. Ex: Mango

o Herbaceous PlantsHerbaceous Plants consist of thin epidermis and contains no foam.

The epidermis contains stomata, gas exchange occurs Ex: Water Lily


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b. Internal StructureThe internal structure of a stem is almost similar to the internal structure of

roots. The internal part of a stem consists of an epidermis, cortex,endodermis, stele, and cambium(dicots plant)

EpidermisEpidermis cell wall in stem is rather thick and covered by a cuticle.

Epidermis layer function is to protect its inner parts

CortexCells in the cortex layer are round with a thin wall. Cortex is the place to

store food

Endodermis


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Endodermis layer is located inside the cortex layer. The endodermis layer of

the stem is unclear and almost united with cortex layer.

SteleStele is the most inner-most part of stem. Inside the stele there are pith,

xylem and phloem. Xylem and phloem form a bundle called theVascular

Bundle

Dicots Stem Monocots Stem

1) Vascular Bundle of a dicots stemIn dicots stem vascular bundle are arranged in a circle. The xylem is

located inside and phloem located outside with the cambium

between them. Inward cambium fission form new xylem (secondary

xylem), while outward cambium fission form new phloem (secondary

phloem). Cambium activity enables a dicot's stem to grow bigger.Growth of the cambium is influenced by water conditions and

nutrients. The more water contain on it, the bigger the diameter of

the xylem. As a result of cambium activity, a dicot stems has clear

borders which are called annual rings

Cambium


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2) Vascular bundle of a monocot stem

In a monocot stem, vascular bundle are scattered and have no

cambium. Since it has no cambium, the stem of a monocot plants will

not grow bigger

FLOWER

The group of plants that produce flowers is anthophyta. According to the experts,

flowers come from leaf modification. Not all plants have flowers

Flower function

Flower function is as a generative reproductive organ. A flower's reproductive

organs are the stamen and pistil. Stamens are the male reproductive organ, and

pistil is the female reproductive organ

Flower structure

Flowers vary in shape and color based on the species or its type. Generally flowers

have the same basic structure, it consists of sepals, petals, stamens, and the pistil


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2.Parts of FruitFruit is composed of seeds, fruit flesh, and fruit wall

In a unripe fruit, the fruit wall doesnt experience tissue division, while in a

ripe fruit, the fruit wall is divided into 3 layers :

a) Outer Layer (epicarp) is hard. Ex: coconutb) Middle Layer (mesocarp) is thick and fleshy. Ex: mangoes, and

papayas

c) Inner layer (endocarp). Some are hard cell layers, others are thin orhave a hard membrane. Ex: rambutan

Fruit WallSeed

Fruit Flesh


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PhotosynthesisPhotosynthesis is the process of converting light energy to chemical energy and

storing it in the bonds of sugar. The process takes place in thechloroplasts,

specifically using chlorophyll

6H2O + 6CO2 --> C6H12O6+ 6O2

Parts of plant that role in photosynthesis

upper and lower epidermal cells: serve primarily as protection for the restof the leaf.

Stomates: let CO2 in and O2 outVascular bundles: part of the plant's transportation system, moving water

and nutrients around the plant as needed.

mesophyll cells: have chloroplasts and this is where photosynthesis occurs.Factors affecting photosynthesis :

Light intensityConcentration of carbondioxideTemperatureWater supply

PLANT MOVEMENT

Plant can move like other microorganism. Based on its stimulus, the movements

in plant are grouped into two :


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1. EXOGENOUS MOVEMENT

2. ENDOGENOUS MOVEMENT

Exogenous Movement

Exogenous Movement is plant movement that is caused by external stimulus like

light, gravitation, water, and etc.

Example: the opening and closing of stomata.

The various kinds of exogenous movements

in plants :

1. Nastic movement

2. tropism movement

3. Taxis movement

Nastic Movement

Nastic movements are plant movements that occur in response to environmental

stimuli but unlike tropic movements, the direction of the response is not

dependent on the direction of the stimulus. Some of the most spectacular plant

movements are nastic movements. These include the closing of the carnivorous

Venus Flytrap leaf when it captures prey or the folding of the mimosa leaf when it

is disturbed.

tropism movement

Tropisms are directional movement responses that occur in response to a

directional stimulus. Plants are not able to relocated if they happen to start

growing where conditions are suboptimal.

Kinds of tropism movement :


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1. Phototropism2. Gravitropism3. Thigmotropism4. Hidrotropism5. Phototropism

Phototropism is directional growth in which the direction of growth is

determined by the direction of the light source. In other words, it is the growth

and response to a light stimulus. Phototropism is most often observed in plants,

but can also occur in other organisms such as fungi. The cells on the plant that are

farthest from the light have a chemical called auxin that reacts when

phototropism occurs.

Gravitropism is a turning or growth movement by a plant or fungus in response

to gravity. Charles Darwin was one of the first to scientifically document

that roots show positive gravitropism and stems show negative gravitropism.

Thigmotropism is a movement in which an organism moves or grows in response

to touch or contact stimuli. Usually thigmotropism occurs when plants grow

around a surface, such as a wall, pot, or trellis. Climbing plants, such as vines,

develop tendrils that coil around supporting objects.

Hydrotropism is a plant growth response in which the direction of growth is

determined by a stimulus or gradient in water concentration. A common example

is plant roots growing in humid air bending toward a higher relative humidity

level. The process of hydrotropism is started by the root cap sensing water and

sending a signal to the elongating part of the root. Hydrotropism is difficult to

observe in underground roots, since the roots are not readily observable, and

root gravitropism is usually more influential than root hydrotropism.

Root grow towards water (positive hydrotropism) and shoot grow away from

water (negative hydrotropism)


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Taxis movement

The movement of a cell or a microorganism in response to an external stimulus.

Certain microorganisms have a light-sensitive region that enables them to move

towards or away from high light intensities (positive and

negative phototaxis respectively). Many bacteria move in response to chemical

stimuli a specific example is aerotaxis, in which atmospheric oxygen is the

stimulus. Taxic responses are restricted to cells that possess cilia, flagella, or some

other means of locomotion.

Endogenous Movement

Autonomic (Endogenous) Movement is caused by stimulus that comes fromthe body of plant itself.Example: the flowing movement of cytoplasm in cell.

Plant DiseasePlants are not free from pest or disease interference. Pest and disease can attack

all parts of a plant body, root, stem, leaf, flower. This can be caused by :Bacteria

Bacteria may cause damage to plants, if the bacteria harm the whole plant, it

will die. In general, they make holes in a fruit or leaves. The example for bacteria

is like parasitic plants, such as mistletoe and dodder. And there are Plant-growth-

promoting rhizobacteri (PGPR) are associated with plant roots and augment plant

productivity and immunity; however, recent work by several groups shows that

PGPR also elicit so-called 'induced systemic tolerance' to salt and drought.

Viruses


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Viruses may also infect plant. They cause appearance of dotted yellow marks on a

leaf. The yellow dots gradually turn darker because the tissues are dead. such a

disease is called a mosaic disease. examples of it are cucumber mosaic virus

(CMV) for cucumber plant , potato virus mosaic (PVM) for potatoes , tobacco

etch virus (TEV) for tobaccos virus and tomato bushy for tomatoes.

FungiFungi can't make their own food, so they must somehow get it from other

organisms, living or dead. Damaged in plants may also be infected by fungi. They

easily contaminate plants because of the spores.Wind makes the spores easily

spread out and attack the xylem. Plant roots absorb water and finally the plant

dies. Fungi called Erysiphe cichoracearum usually infect the surface of leaf and

young stem, making the leaves yellow and finally dead.

InsectsInsects the most successful animals on Earth. Of all the millions of animals on our

planet, Most insects help plants to carry the pollen from one flower to another.

But there are insects that harm plant such as small insects (bees) and fruit flies.

The insects pick up some microbes from infected plants and move them to others.

They usually eat most of the leaves so that it impossible for the plants to make alot of food in their body.

ProtozoaPlant diseases caused by protozoa. They are transmitted as zoospores which are

very durable, and may be able to survive in a resting state in the soil for many

years. They have also been shown to transmit plant viruses. When the motile

zoospores come into contact with a root hair they produce a plasmodium and

invade the roots.

Parasitic plantsParasitic plant is one that derives some or all of its sustenance from another

plant. This plant can make the another plants die because the deficiency of the

plants nutrients.


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The Example of Plant Diseases are :

Soft Rot DiseaseAttack the neck newly grown roots, caused by fungi. Plant can no longer

support the stem an then collapse

Powdery Mildew DiseaseAttack growing seed, seed become spongy and finally dies. Caused by fungi.

The infected plant will become short with black spot on the leves, and

decreased production. Caused by fungus

CVPD ( Citrus vein phloem degeneration)Attack the phloem of an oranges stem. Leaf buds become small, turn yellow

so they become yellow fruit. Caused by bacteria

Tobacco mosaic diseaseTMV (Tobacco Mosaic Virus) causes white spots on tobaccos leaves which

lead to decrease in the quality of the leaf

all about plants summary

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