Introduction to Plant BiologyClassification and Structure

TY Biology

Introduction to Plant Structure

Learning Outcomes….

• Identify the parts and organs in a flowering plant and give their functions.

• Label a diagram of a cross section of a leaf, identify and give the function of each part.

Plant Structure

• Plants like all living things are made up of Cells, Tissues and Organs.

• Cells – variety of cells which carry out specific functions –

Palisade cells contain chloroplasts

• Tissue – xylem and phloem are example fo plant tissue

• Organs - including roots, leaves, the stem and

reproductive organs.

Each organ has its own functions.

Together, the organs of a plant allow it to carry out

the processes of life.

Plant Tissue

• Dermal tissue – this tissue lies on the surface of plants protect the plants from losing water.

• Ground tissue – This makes up the root vascular and epidermal system and is responsible for plant photosynthesis, storage of water/food and the plant support system.

• Vascular Tissue – this tissue is made up of xylem, phloem, and cambium cells, with its functions including transportation of water (xylem), transportation of food (phloem), minerals, hormones in the plants.

The Plant Root

• The roots help provide support by anchoring the plant firmly in the ground and absorbing water and nutrients needed for growth.

• Water and minerals are absorbed the root hairs.

• Roots can also store sugars and carbohydrates that the plant uses to carry out other functions.

Tap roots

Generally large and

fleshy in

appearance

grow deep into the ground to search for water

Can store food as carbohydrate

Fibrous roots

Often growing

beside taproots:

Collecting water

before it sinks

deep into the

ground,

lie close to

the surface of

the soil,

are developed to help the plant climb for example, ivy

Adventitious Roots

The Stem

• Stems hold the leaves and give the plant shape.

•water and minerals is carried up from the roots to the leaves through xylem tissue.

•food is transport from the leaves to the rest of the plant via Phloem tissue.

• Stems can act as a food store (e.g. celery and rhubarb stems)

The Plant Leaf

• One of the primary functions of a leaf is to

support Photosynthesis.

• They enable a plant to make its own food.

• They contain Stomata which allow the

movement of carbon dioxide, water vapour and oxygen in and out of the leaf.

Anatomy of a Plant Leaf

Terminology• Cuticle - is a protecting film covering the epidermis of leaves.

• Epidermis – outer layer of cells on a leaf or stem

• Palisade Layer – elongated cells containing chloroplasts

found below the epidermis

• Mesophyll Layer –allows for the interchange

of gases (CO2 and H2O) that are needed for photosynthesis.

• Xylem – Transport water and minerals around the plant

• Phloem – transport food (Glucose) around the plant

• Stomata – opening on the underside of a leaf to allow gases

move in/out of the leaf

Stomata

• Stomata are tiny openings in the underside of leaves.

• They enable the movement of gases (Oxygen and Carbon Dioxide) and water vapour in and out of the plant leaf.

• Guard cells on either side of a stoma help to regulate the rate of transpiration by opening and closing the stoma

Guard cell

The Plant Flower

• Flowers are modified leaves and are the reproductive part of the plant.

• The produce seeds which are dispersed and grow into the next generation.

• Flowers contain the male (pollen) and female (egg).

• They use scent and colour to attract insects and small birds and animals and reward them with nectar ususally found at the base of the flower.

Plant Flower Structure

The Plant Flower

• Stamen – male reproductive part consisting of the filament and Anther

• Anther - Produce male sex cells (pollen grains)

• Filament – supports the Anther

• Pistil (Carpel) – Female reproductive part consisting of the stigma, style and ovary

• Stigma - The top of the female part of the flower which collects pollen grains.

• Style – Carry the pollen grain to the ovary

• Ovary - Produces the female sex cells (contained in the ovules)

The Plant Flower

The Plant Flower• Sepal – outer bud leaves

protecting the flower

• Petal – Their main function is to attract pollinators and also protect the inner reproductive structures of a flower.

• Receptacle Its main function is to both connect the stalk to the flower and to support the flower.-

Summary• The roots help provide support by anchoring the plant

firmly in the ground and absorbing water and nutrients needed for growth.

• Stems hold the leaves and give the plant shape and transport food and water around the plant.

• One of the primary functions of a leaf is to support Photosynthesis.

• They enable a plant to make its own food.

• Flowers are modified leaves and are the reproductive part of the plant.

• The produce seeds which are dispersed and grow into the next generation.