Unit 5 Section 2: Plant Structures

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Unit 5 Section 2: Plant Structures

The Aroid plant has the largest leaves on Earth, at three meters long. This is comporable to the height of a basketball hoop from the ground These large leaves help the plant to grow and produce flowers and fruit.

Multiple Choice

What is the sharpness (clearness) of an image?

• revolution

• resolution

• revelation

• solution

Dropdown

A ​

Select answer

microscope has more than one lens.

Multiple Choice

To find the total magnification power of a microscope, you need to

• add the power of the eyepiece (ocular) by the power of the objective lens

• divide the power of the eyepiece (ocular) by the power of the objective lens

• subtract the power of the eyepiece (ocular) by the power of the objective lens

• multiply the power of the eyepiece (ocular) by the power of the objective lens

Labelling

Label each part correctly. Be careful!!

Drag labels to their correct position on the image

eyepiece or ocular lens

fine adjustment knob

light source

base

diaphragm

low power objective

coarse adjustment knob

arm

Learning Objectives

• Describe the functions of roots, and stems

• Describe the parts that make up a root

• Describe the parts that make up a stem

• Describe the functions of leaves, seeds, and flowers

• Understand how seeds become new plants

• Describe the structure of a flower

Parts of a Plant

• There are many different structures of a plant, each one plays an important role

• The three main structures we will look at are:

  • Roots

  • Stems

  • Leaves

Roots

• Roots have three functions in a plant

  • Anchor a plant in the ground

  • Absorb water and minerals from the soil

    • The more roots a plant has, the more it can absorb

  • Store food

• Roots are sorted into two different types

Fibrous Roots

• Fibrous Roots: made up of many similarly sized roots that form a dense, tangled mass

  • Can pick up a lot of soil when pulled from the ground

  • Examples: grass, corn, onions

Taproots

• Taproots: made up of one thick main root, with smaller roots branching off the main roots

  • Hard to pull out of the ground

  • Examples: Carrots, dandelions, and cacti

Root Structure

• Root Cap: protects the root from injury as the root grows through the soil

  • Cells directly behind the root cap divide to form new cells

• Root Hairs: grow out of the surface of the root

  • Can enter tight spaces in the soil

  • absorb water and minerals

  • Provide extra support

Root Tissue

• The inside of the root contains vascular tissue, which carries materials throughout the plant

  • Xylem: Carries water and nutrients up from the roots to the leaves/stem/other parts of the plant

  • Phloem: Carries food produced by leaves to the roots for storage or growth

Multiple Choice

What is the primary function of the root cap?

• To protect the root as it grows

• To Aachor the plant in the ground

• To transport nutrients from the soil to the upper parts of the plants

• To transport materials from the leave to the root

Multiple Choice

What is the function of the xylem?

• To protect the root as it grows

• To reach into the soil for nutrients and water

• To transport nutrients from the soil to the upper parts of the plants

• To transport materials from the leave to the root

Multiple Choice

What is the function of the root hairs?

• To protect the root as it grows

• To reach into the soil for nutrients and water

• To transport nutrients from the soil to the upper parts of the plants

• To transport materials from the leave to the root

Multiple Choice

What is the function of the Phloem?

• To protect the root as it grows

• To reach into the soil for nutrients and water

• To transport nutrients from the soil to the upper parts of the plants

• To transport materials from the leave to the root

Stem Functions

• All stems have two main functions:

  • Carry materials between the plant's roots and leaves

  • Provide support for the plant and hold leaves up to the sun

• Some stems also store extra food for the plant

  • Example: Asparagus

Stem Types

• Two types of stem:

  • Woody: hard and rigid

  • Herbaceous: soft and somewhat flexible

• Both Contain phloem and xylem tissues

Outer Layers of Woody Stems

• Woody Stems have many different layers of supporting cells

• Bark: The outermost layer of a woody stem

  • Cork: a hard protective layer of bark

  • Phloem: The inner layer of bark

Inner Layers of Woody Stems

• Cambium: The second layer of a woody stem

  • divides up to make new phloem and xylem

  • makes up the "wood" of the tree

    • Sapwood: active xylem that transports water and minerals through the stem

    • Hardwood: older inactive xylem that gives a tree support

Annual Rings

• Annual Rings: The rings you see inside a tree that show the yearly growth

  • Both light and dark rings are made up of xylem

    • Xylem that forms in the spring grows rapidly

      • are large with thin walls

      • Have a lighter color

    • Xylem that forms in the summer grows more slowly

      • are smaller and have thicker walls

      • Have a darker color

  • One pair of light and dark rings represent one year of growth

  • Can indicate how conditions were each year

Multiple Choice

A tree has 24 light rings and 24 dark rings. How many years old is the tree?

• 24

• 48

• 12

• 576

Multiple Choice

This is the hard outer layer of bark that protects the inside of the tree

• Cork

• Sapwood

• Hardwood

• Cambium

Multiple Select

Select all of the possible functions of a stem

• To carry substances between the roots and leaves

• To anchor a plant in the ground

• To store food

• To provide support for a plant

• To break apart soil

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

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

The Structure of Leaves

• 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 while oxygen and water vapor exit

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

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

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

• There are three main parts to a seed

Seed Structure

• 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

• 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

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

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

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

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

Sepals and Petals

• 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

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

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

Dropdown

​

Select answer

are the most colorful parts of a flower, and attract pollinators, while ​

Select answer

are an outer structure that protects the developing bud.

Dropdown

​

Select answer

are the male reproductive part of the flower and produce pollen. ​

Select answer

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