Lesson 7.1.2: Plant Structures: Leaves and Flowers

Lesson 7.1.2: Plant Structures- Leaves, Seeds & Flowers

The Rafflesia flower can grow up to one meter wide and weighs seven kilograms. When it blooms, it has a smell similar to rotting meat and is known as "The Death Flower"

Multiple Choice

True or false: The stem of a plant is a single solid structure with no layers

• True

• False

Multiple Choice

Which part of the plant is responsible for the absorption of nutrients

• Stem

• Flowers

• Roots

• Leaves

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carries water and nutrients from the roots to the rest of the plant, while​

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carries material to the roots for growth.

Drag these tiles and drop them in the correct blank above

Xylem

Phloem

The Root Cap

Root Hairs

Cambium

Cork

Lesson Objectives

• Describe the functions of leaves, seeds and flowers

• Understand how seeds become new plants

• Describe the structure of a flower

Leaves

• Leaves can vary greatly in size and shape

  • Can be long and broad like a maple leaf, or thin and skinny like a pine tree needle

• Leaves Capture the sun's energy and carry out photosynthesis

Grade 8 Science Ohio | Lesson 7.1.2

The Structure of Leaves

• Leaf Surface

  • The outer surface is the cuticle and has a waxy coating

    • Helps keep water in the plant

  • Stomata: small pores on a leaf that open and close to control the flow of gases in and out of the leaf

    • When open, Carbon dioxide enters, and oxygen and water vapor exit

Grade 8 Science Ohio | Lesson 7.1.2

Leaves & Photosynthesis

• Chloroplasts: specialized cells in a leaf where photosynthesis takes place

  • Are located close to the leaf's surface, and trap energy from sunlight

• Carbon dioxide enters the stomata

• Water travels through the xylem from the roots

Grade 8 Science Ohio | Lesson 7.1.2

Controlling Water Loss

• Transpiration: The process by which water evaporates from a plant's leaves into the air

  • If a plant starts to become too dry, the stomata will close up to prevent too much water loss

Grade 8 Science Ohio | Lesson 7.1.2

Multiple Choice

If you forget to water a houseplant for a few days, would the stomata be open or closed?

• Open

• Closed

Multiple Choice

What is the primary function of leaves

• To shade the roots of a plant

• To control water loss

• To capture the sun's energy for photosynthesis

• To protect the plant

Seeds

• Many plants begin their lives as seeds

• Every seed contains a partially developed plant

• If a seed lands in an area where conditions are favorable, the plant sprouts out of the seed and begins to grow

Grade 8 Science Ohio | Lesson 7.1.2

Seed Structure

• There are three main parts to a seed

  • Embryo: the young plant that develops from the fertilized plant

    • Already has the beginning of roots, stems, and leaves

    • Usually stops growing until conditions are good

Grade 8 Science Ohio | Lesson 7.1.2

Seed Structure

• There are three main parts to a seed

  • Cotyledon: Stored food for the embryo to use for growth

  • Seed Coat: The outer covering of a seed that protects the embryo and keeps it from drying out

Grade 8 Science Ohio | Lesson 7.1.2

Seed Dispersal

• After seeds form, they are usually scattered

  • The farther away a seed lands, the better chance it has at survival

• Dispersal: The Scattering of seeds

  • Occurs in many different ways

    • Animals eat fruit and pass the seeds through the digestive system

    • Hooking onto the fur of animals

    • Falling into the water and being carried to new places

    • Wind carries seeds

    • Ballistic Scattering: The plant explodes and sends the seeds flying

Grade 8 Science Ohio | Lesson 7.1.2

Germination

• After a seed is dispersed, it may remain inactive for a while

• Germination: the moment a plant begins to grow and pushes out of the seed

  • Is started when a seed absorbs water

  • Uses the food stored in the cotyledon to grow

  • Roots grow first, then the stem

Grade 8 Science Ohio | Lesson 7.1.2

Flowers

• Flower: The reproductive structure of an angiosperm

  • Flowers have all different shapes, sizes, and colors, but the same function: Reproduction

• Pollination: The transfer of pollen from male reproductive structures to female reproductive structures

Grade 8 Science Ohio | Lesson 7.1.2

Flower Structures

• A typical flower contains the following parts

  • Sepals

  • Petals

  • Reproductive structures

    • Stamens

    • Pistils

    • Some plants have both structures in a single flower, while others have only one

Grade 8 Science Ohio | Lesson 7.1.2

Sepals and Petas

• Sepals: leaflike structures that protect a developing bud

  • are often green

• Petals: The most colorful part of the flower

  • Are designed to attract specific pollinators to come to the flower

Grade 8 Science Ohio | Lesson 7.1.2

Stamens

• Stamens: The male Reproductive structure in plants

  • Has two parts

    • Filament: a thin stalk that holds the anther

    • Anther: the part of the plant that produces pollen

Grade 8 Science Ohio | Lesson 7.1.2

Pistils

• Pistils: The female reproductive structure in plants

  • Generally in the center of most flowers

  • Some plants have multiple pistils

  • Parts:

    • Stigma: sticky top part of the pistil

    • Style: Long tube that connects the stigma to the ovary

    • Ovary: the base of the Pistil that protects the seeds as they develop

Grade 8 Science Ohio | Lesson 7.1.2

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are small leaf-like parts of a flower that protect the developing flower.

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are the most colorful flower, and attract pollinators.

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are the male reproductive part of the flower and produce pollen

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are the female reproductive part of the flower and protect the developing seed.