Plant Processes and Reproduction LESSON XBellringer

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

LESSON 1

Active Lives

Day after day, palm trees sway in the breeze. However, that is not all they do. They are active in many ways. They bring water from the soil to their leaves. Their trunks grow taller and wider. They produce fruits and seeds as a part of their reproductive cycles.

The processes in a palm tree’s life require energy. Taking in and using energy is something that plants, animals, and all living things do throughout their lives.

1 How are plants and other living things alike? How are they different?

2 What is the source of energy for plants?

3 How does the palm tree benefit from having all of its leaves at the top of the tree?

Carbon dioxideCO2

OxygenO2

Lightenergy

WaterH2O Sugar

C6H12O6

Light energy

Chlorophyll6CO2 + 6H2O C6H12O6 + 6O2

Photosynthesis

Carbon dioxide + Water Sugar + Oxygen

Plant Processes and Reproduction

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

Focus on Content LESSON 1

Photosynthesis

Plant Processes and Reproduction Bellringer

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

Sunflowers and the Sun

Do you notice anything odd about these sunflowers? Their blooms all point in the same direction. The explanation for this begins with the source of their name.

In the bud stage, the head of a sunflower tracks the Sun’s position in the sky during the day. When the bud blooms, it stops moving. The flower typically faces to the east.

Other plants also track the Sun. Many plants have leaves or stems that move in response to the Sun’s movement.

1 Why is sunlight important for plants?

2 How might a plant benefit by having leaves that move in response to the Sun?

LESSON 2

Plant Processes and Reproduction

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

Focus on Content

Photoperiodism

LESSON 2

Long-dayplant: carnation

Short-dayplant: poinsettia

Day-neutralplant: rose

Early summer

Late fall

Midnight

Midnight

Noon

Noon

6 A.M.6 P.M.

6 A.M.6 P.M.

Plant Processes and Reproduction Bellringer

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

Look at Me!

When you see an attractive flower, does it catch your attention? People all over the world enjoy the beautiful flowers of many plants such as this lily.

In nature, flowers attract smaller admirers, including bees, other insects, and certain kinds of birds and bats. These animals visit flowers to gather nectar, a sweet liquid that flowers produce. The animal visitors help the flower serve its purpose, which is to make seeds.

1 How is a flower different from other parts of a plant?

2 Why are bees and other animals attracted to flowers?

3 Describe the flower parts you see in the photo.

LESSON 3

Stigma Pollen grainPollen tube

Stamen- AntherFilament

StyleOvary

Ovule

Sperm (haploid)Egg (haploid) Ovule

FERTILIZATIONOvule

Zygote(diploid)

Embryo(diploid)

SeedSeedSprouting seedDiploid seedling

Plant Processes and Reproduction

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

Focus on Content LESSON 3

Reproduction in a Flowering Seed Plant

Mature plant(diploid)

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

Teacher GuidePlant Processes and Reproduction Lesson 1 Bellringer Goodshoot/PunchStockActive Lives

The term palm tree applies to thousands of related species. Many palm trees thrive only in warm, tropical climates. But some hardy species live as far north as Canada.

All trees take up water from the soil. For a palm tree, this means that water must rise 6 m (20 ft) or higher off the ground. Most of this water then evaporates from openings in the trees’ leaves (fronds). The energy for this process ultimately comes from the Sun, which also provides the energy for photosynthesis.

Answers to Questions 1 Like all living things, plants grow and change, they

reproduce, and they take in and use energy. Plants differ from other living things because they use sunlight to make their food rather than taking in food from other sources.

2 Light energy that comes from the Sun is the energy source for plants.

3 On many trees the upper leaves block the sunlight, sometimes leaving only a little light for the lower leaves. Palm trees do not have this problem because they have no lower leaves.

Lesson 1 Focus on Content The McGraw-Hill CompaniesPhotosynthesis

Use the transparency to point out the substances used in photosynthesis (carbon dioxide and water) and the substances that photosynthesis produces (glucose and oxygen). Animals, including humans, could not survive without the oxygen and glucose that photosynthesis produces.

A type of algae was the first organism to perform photosynthesis. Before this algae existed, Earth’s atmosphere had little to no oxygen. Today, because of the actions of plants and algae all over Earth, the atmosphere is 21 percent oxygen.

Lesson 2 Bellringer Brand X Pictures/PunchStockSunflowers and the Sun

The daily motion of a sunflower is an example of heliotropism, which is a response to the Sun. Scientists are not certain how this response helps the sunflower.

Answers to Questions 1 Sunlight provides the energy for photosynthesis—

the process by which plants make the food they need.

2 Photosynthesis takes place in a plant’s leaves. By moving to face the Sun, its leaves can receive more sunlight on their surface and thus receive more energy.

•

•

•

•

•

Lesson 2 Focus on Content Photoperiodism

Remind students that the number of hours of darkness differs from season to season. By flowering only when exposed to certain hours of darkness, plants will flower according to the seasons.

Many long-day plants, such as spinach, do not bloom in the tropics, where hours of darkness equal the hours of daylight nearly all year long. For similar reasons, some short-day plants grow poorly in the Far North.

Lesson 3 Bellringer Annie Reynolds/PhotoLink/Getty ImagesLook at Me!

A lily is an example of a perfect flower, meaning it has both stamens (male reproductive organs) and pistils (female reproductive organs). Imperfect flowers have either stamens or pistils, but not both.

Remind students that in everyday language, the word flower describes a plant that makes large, attractive blooms. In scientific use, however, the flower is only the bloom, not the whole plant.

Answers to Questions 1 Possible answers: Flowers have unique parts,

including petals that often are colorful and delicate; flowers typically last only a short time; flowers have a unique purpose, which is to make seeds.

2 They are attracted by the bright colors and patterns and the smell of nectar.

3 Answers include: the large, white petals; stem and leaves; the stigma at the top of the long tube called the style; and the six red-tipped anthers supported by six filaments.

Lesson 3 Focus on Content Reproduction in a Flowering Seed Plant

Remind students that pollen grains from one flower may be transferred to the stigma of another flower, a process called cross-pollination.

The mature diploid plant produces flowers. A haploid pollen grain travels from the anther to the stigma where pollination occurs. A pollen tube grows to reach the egg in the ovary. Sperm are released from the pollen tube to fertilize the egg. This results in a zygote that develops into an embryo. The seed develops from the ovule, while the fruit develops from the ovary. The seed can then sprout, thus continuing the life cycle.

•

•

•

•

•

•