Download Plant Reproduction

Unit 8
Plant Reproduction
Scientific Basis
Unit Breakdown
This unit examines the processes of plant reproduction,
through which the perpetuation of species is achieved.
Students have covered the morphology of plants and their
classification as trees, bushes and grasses in previous books
of the series. This unit focuses on plant reproduction. The
study of sexual reproduction is limited to flowering plants.
The study centers on the morphology of the organs
responsible for plant reproduction—stamen, pistil, and the
like—and on ordering the processes involved—pollination,
fertilization and germination.
In the first lesson, students will investigate the differences
between sexual and asexual reproduction.
In the second lesson, students will review the parts of a
flower and learn characteristics of fruits and seeds.
In the final two lessons, students will explore pollination,
fertilization and germination—fundamental steps in plant
reproduction.
Contents
Unit Outline
Concepts
Plant Reproduction
Types of plant reproduction.
The flower as a reproductive organ.
Fruits and seeds: types, functions and dissemination.
Types of
Plant
Reproduction
Flowers,
Fruit and
Seeds
From
Flower to
Fruit
Germination
and Growth
Stages of reproduction.
The life cycle of plants. Seasonal changes in plants.
Cultivation of plants.
Procedures
Solution of problems related to plant reproduction.
Society/
Investigate
Greenhouses/
Animal
Pollination
Health
Education
Wash Fruit
before You
Eat It
Interpretation of diagrams, sequences and graphs.
Test Your
Knowledge
Chronological ordering of the processes involved in plant
reproduction.
Attitudes
Interest in learning more about plants.
Appreciation of the importance of plants and interest in
caring for them.
Development of habits associated with the protection and
conservation of ecosystems.
100
8
Plant Reproduction
LOOK
1. Plants.
• How many different types of plants
can you see in the photograph?
Describe them.
• How are they different?
• Which of the plants have flowers?
2. This photograph was taken in spring.
Imagine the landscape in winter.
Draw it.
• Would you see the same plants in
winter? Would there be any flowers?
• What would the trees look like?
Notes
W H AT D O Y O U K N O W ?
1. Answer the questions.
• Why do we plant seeds?
• What part of a plant contains seeds?
• Is a potato a type of fruit? What
about a tomato?
2. Taking care of a plant.
Bring a geranium in a flowerpot to
class. Answer these questions.
• What do plants need to grow? How
should we take care of the
geranium?
Take care of the geranium for a year.
Check your answers to the questions.
81
Look
Have students look at and describe the photo. In pairs, have them answer
the questions. Ask some pairs to report their answers to the class.
What do you know?
Ask students if they have plants at home and where they keep them. Invite
them to describe their plants and to talk about where they came from, who
takes care of them, what they need to live, and so on. Have students
answer the questions. Encourage them to take care of a geranium or
similar plant in the classroom.
Answer Key
Look: 1. • Two (trees and grasses). The trees are tall with a brown trunk and green
leaves. The grasses are short with green stems and leaves and pink flowers. • The trees
are taller and have thicker stems. • The grasses. 2. • Yes. No. • The evergreen trees in
the background would look the same. The deciduous tree in the foreground would not
have leaves.
What do you know? 1. • To grow new plants. • The fruit or the cone. • No (the potato
is a tuber, or underground stem). Yes. 2. • Soil, water, air and light. We should water it
often, fertilize it, put it in a suitable place and replant it in a bigger pot as it grows.
101
1. Types of Plant Reproduction
1. Types of Plant
Reproduction
tuber
Concepts
Types of plant reproduction. The
flower as a reproductive organ.
Vocabulary
Asexual reproduction, bud, bulb, cutting,
female sex cell, flower, leaf/leaves, male
sex cell, seed, sexual reproduction, stem,
stolon, tuber.
stolons
bulb
The bulb and leaves of an onion.
The tuber and flowers of a
potato plant.
Materials
Photographs of a variety of plants.
Types of Plant Reproduction
This lesson may be used to review
the following language:
There are two kinds of plant reproduction: sexual
reproduction and asexual reproduction.
• The part of the plant responsible for sexual
reproduction is the flower.
• Asexual reproduction occurs when a new
plant grows from the stem or leaves of an
existing plant.
All plants can reproduce by sexual reproduction.
Some plants can reproduce by both methods.
Might
Sexual Reproduction
The fruit of one might be smaller than
the fruit of the other.
Flowers are responsible for sexual reproduction in
plants. A male sex cell and a female sex cell unite
inside a flower. The fruit and seeds develop from
the flower. Later, a new plant develops from a seed.
When a plant reproduces by sexual reproduction,
there are differences between the parent plant
and the offspring plant. For example, the color
of their flowers might be different. The fruit of one
might be smaller than the fruit of the other.
One might be more resistant to certain illnesses
than the other.
Some plants, like ferns, do not have flowers.
However, these plants also produce sex cells and
are capable of sexual reproduction.
Expressing Concepts
Focus on Science
Questions
Human and Plant Reproduction
1. How do plants reproduce?
Review students’ knowledge of
human reproduction: What organs
are there in the male and female
reproductive systems? What occurs
during fertilization? (A male and a
female sex cell unite.) How does a baby
change as it grows?
2. How can a new plant grow
from an existing plant?
Explain that flowers also have male
and female organs, which produce
male and female sex cells. The
offspring of many plants are very
similar, but not identical, to the parent
plants. The offspring of some plants
(those that can reproduce asexually)
are identical to the parent plants.
Elicit the names of the parts of a plant
and the functions they perform
(leaves—nutrition and respiration;
stem—support for the flower and
leaves, transportation of sap; roots—
absorption of water and nutrients
from the soil; flowers—reproduction).
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The flowers and stolons of a
strawberry plant.
3. What do flowers do?
82
Types of Plant Reproduction
Show photos of plants and ask students to identify the parts (root, leaves,
stem, flowers). Have students read the text and answer Questions 1 and 2.
Sexual Reproduction
Ask students how animals and plants are similar (e.g., they grow, feed,
breathe, reproduce and die). Then have them review the process of
fertilization in humans (a male and a female sex cell unite in a fallopian
tube). Explain that plants also have male and female organs that produce
male and female sex cells. Unlike most animals, which are either male or
female, most plants have both male and female organs in their flowers.
Ask students to read the text and answer Question 3. Explain that sexual
reproduction is so called because the process involves sex cells.
Asexual Reproduction
Have students read the text and look at the photos on page 82. Ask them
what the main difference between sexual and asexual reproduction is (sex
cells are not involved in asexual reproduction).
Compare and Analyze
Cuttings
Asexual Reproduction
The stem or leaves of a plant are involved in asexual
reproduction.
Tubers, bulbs and stolons are types of stem.
• Tubers are stems in the soil. Buds sprout from the
tubers. The buds produce new plants.
• Bulbs are also underground stems. Bulbs have a
bud inside them. The bud produces a new plant.
• Stolons are stems above the ground. New stolons
produce new plants.
When a plant reproduces by asexual reproduction,
the new plant is identical to the original plant.
Plants that reproduce by asexual reproduction can
also reproduce by sexual reproduction.
Language Skills: Writing
Cuttings allow us to grow new plants
from existing adult plants. To grow a
plant from a cutting, first take an
existing plant. Cut off a branch with
several leaves. When you plant the
branch, roots will grow out of it. The
roots take hold in the soil and the
branch begins to grow and develop.
This kind of asexual reproduction does
not happen naturally. It is a technique
we use to produce specific plants, like
geraniums and roses.
Parks and Gardens
Have students write a detailed
description of a public park they
know well, where there are a variety
of trees, shrubs, flower beds, and the
like. Alternatively, have them write
detailed descriptions of the trees and
plants in their yards or gardens.
Cross-Curricular Connection
Geranium
Environmental Education:
Deforestation and Reforestation
• Explain what you must do to grow a
geranium from a cutting.
• Do plants reproduce from cuttings
naturally? Why or why not?
Tulips have flowers and bulbs.
Materials: Construction paper
(1 sheet per pair).
Discuss the problem of deforestation
in many parts of the world, where
trees are cut down for lumber or to
make way for road construction or
farmland. Deforestation can result in
desertification of some areas, causing
drought, reduction of food supplies
for many animals and destruction of
their habitats.
Activities
1
Complete the sentences.
sexual reproduction
asexual reproduction
• Bulbs, tubers and stolons are involved in
• The potato plant can reproduce by
Flowers are responsible for in
2
•
involves the sex cells.
•
involves stems and leaves.
.
and by
.
.
Which of the following sentences is correct? Explain.
a) Some plants can reproduce sexually and asexually.
b) If a plant reproduces sexually, it cannot reproduce asexually.
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In pairs, have students make illustrated charts with the three types of
asexual reproduction and their characteristics.
Point out that some animal groups also reproduce asexually. A starfish (an
echinoderm) can grow from a single arm of an adult starfish.
Have students do the Activities in pairs. Have some pairs report their
answers to the class.
Elicit the meaning of the word
reforestation. Discuss how our
knowledge of plants and their
reproductive processes (e.g., the time
of year they are fertilized or if they
can reproduce asexually) makes it
possible to grow new trees where
older trees used to be.
In pairs, have students make posters
promoting reforestation.
Activities
Answer Key: 1 • asexual reproduction. • asexual reproduction; sexual reproduction;
sexual reproduction. • Sexual reproduction. • Asexual reproduction. 2 Sample answer:
Sentence a) is correct. All plants can reproduce sexually; some plants, like the onion,
the potato and the strawberry, can also reproduce asexually.
Compare and Analyze: Cuttings
Ask students what decorative plants they have at home. Have them read
the text. In pairs, have them discuss and do the activity.
Answer Key: • Take an existing plant and cut off a branch with several leaves on it.
Plant the branch. • No. A branch cannot fall off and plant itself voluntarily.
103
2. Flowers, Fruit and Seeds
2. Flowers, Fruit and
Seeds
The Parts of a Flower
Fleshy Fruits
corolla
pistil
Concepts
The flower as a reproductive organ.
Fruits and seeds: types, functions and
dissemination.
stamen
stigma
anther
style
filament
ovary
sepal
petal
Vocabulary
Anther, calyx, corolla, filament, fleshy
fruit, nut, ovary, petal, pistil, sepal,
stamen, stigma, style, sunflower.
calyx
Nuts
protective
casing
nut
Chickpeas
Almond nuts on an almond tree.
Chestnut
The Parts of a Flower
Expressing Concepts
This lesson may be used to review
the following language:
Adverbs of frequency
Flowers usually have several stamens.
Focus on Science
Questions
Plant Reproduction
1. Describe flowers.
Materials: Flowers, scalpels (per
pair); paper.
Focus students’ attention on The
Parts of a Flower diagram on page 84
of their books. Divide the class into
pairs and distribute materials. Have
each pair cut a cross section of their
flower, draw it and label the parts.
Display students’ diagrams around
the classroom. Encourage students to
compare the parts of different kinds
of flowers.
The fruit of a blueberry
bush.
Seeds
Materials
Photographs of a variety of flowers.
Explain that, like all other living
things, plants eventually die. To
ensure the perpetuation of the species,
they have to reproduce themselves.
Emphasize that a flower has male and
female parts, and that, as in other
types of sexual reproduction, both
male and female sex cells are
necessary to create new plants.
The fruit of a strawberry
plant.
The flower is the reproductive unit of flowering
plants. The parts of a flower include the following:
corolla, calyx, pistil and stamen.
• The corolla is the colorful part of the plant. Petals
form the corolla.
• The calyx is at the bottom of the flower. Sepals
form the calyx. The sepals are small green leaves
that protect the flower before it opens.
• The pistil has three parts: a stigma, a style and
an ovary. The ovary produces the female sex
cells, called ovules. The style is usually shaped
like a bottle. The tip of the pistil is called the
stigma.
• The stamen has two parts: a filament and an
anther. The anthers produce pollen. The male sex
cells, or sperm, are in the pollen. Flowers usually
have several stamens.
2. Describe seeds.
3. What kinds of fruit and nuts
are there?
84
The Parts of a Flower
Show photos of flowers and ask students to identify the different parts,
using The Parts of a Flower diagram.
Explain that some parts of a flower, such as the pistil and the stamen, are
related to reproduction, while others, such as the calyx (the collective term
for the sepals) and petals, protect the other parts. Petals also attract animals,
which play a role in plant reproduction. Point out that there are a great
variety of flowers: some have fused petals, such as the bellflower; some have
many stamens, such as the honeysuckle; others have few, such as the orchid.
Have students read the text. Encourage them to locate on the diagram the
parts mentioned in the text. Then have them answer Question 1. Ask
students to copy the diagram in their notebooks and label the parts with
short texts describing their functions. Then have them do Activity 1.
Seeds
Explain that some fruits, such as the strawberry, have their seeds on the
outside, but other fruits have their seeds on the inside. Have students read
the text and answer Question 2.
104
Look
Seeds
The Sunflower Is Not a Flower
Seeds form inside fruit. Some fruit, like the peach,
only have one seed. Other fruit, like the apple,
have several.
Seeds have a protective covering. The covering of
some seeds, such as peas, is very thin. Other seeds
are harder, like watermelon seeds. The covering of
some seeds is hard and thick, like the apricot seed.
Although the sunflower looks like a
flower, it is not a single flower. A
sunflower is a group of many flowers.
Language Skills: Reading
The Colon
special leaves that
protect the flowers
Fruits
Ask students to find sentences with
colons in the text (The parts of a flower
include the following: corolla, calyx,
pistil and stamen. The pistil has three
parts: a stigma, a style and an ovary.).
Ask what function the colon has (to
introduce a list of related items).
stigma
After fertilization, part of a flower develops into
a fruit.
• Fleshy fruits accumulate water. Grapes,
cucumbers, apples, oranges, strawberries,
peppers, etc. are all fleshy fruits.
• Nuts do not accumulate water. Acorns,
chestnuts, almonds, peanuts, etc. are all nuts.
anthers
flowers
petals
A Single Flower
Write the following notes on the
board and have students turn them
into complete sentences using a
colon in each:
• Describe a sunflower.
What are its flowers like?
• What other plant has flowers in
groups but looks like a single
flower?
Activities
1
reproduction—sexual, asexual
the stamen—filament, anther
Read the key words. Look at the pictures. Put the key words in the correct box.
Explain what each part of the flower does.
stigma
petal
anther
filament
ovary
Cross-Curricular Connection
Art: Paper Flowers
Materials: Paper, construction paper,
green paper, tissue paper (various
colors), modeling clay, thin and
regular wire.
2
Draw the following fruit with their seeds in your notebook.
Complete the tables.
peach, melon, apricot, plum, tomato, cucumber, apple, pear, green pepper
Fruit with One Seed
Fruit with Several Seeds
Seeds with a Thin Covering Seeds with a Thick Covering
85
Fruits
Explain that some seeds are often mistaken for nuts (e.g., brazil nut,
almond, pistachio). The term fruit refers to the container for the seeds; this
may or may not be edible. Have students read the text, look at the photos
of fruits and answer Question 3. In pairs, have students do Activity 2.
Ask students to study carefully The
Parts of a Flower diagram on page 84
of their books. Then, using the
diagram as a guide, have them design
and make three-dimensional models
of flowers. Show them how to use
wire wrapped in green paper for the
stem, construction paper for the
sepals, tissue paper for the petals,
thin wire for the style and the
filaments, and small balls of modeling
clay for the stigma and anthers.
Activities
Answer Key: 1 Clockwise from top left: petal, stigma, filament, anther, ovary; petal, stigma,
anther, ovary, filament. The stigma is part of the pistil. The petals protect other organs and
attract animals. The anthers produce the male sex cells. The filaments support the anthers.
The ovary produces the female sex cells. 2 One Seed: peach, apricot, plum. Several Seeds:
melon, apple, cucumber, pear. Thin Covering: green pepper, apple, melon, tomato,
cucumber, pear. Thick Covering: peach, apricot, plum.
Look: The Sunflower Is Not a Flower
Explain that sunflowers turn during the day so that their flowers always
face the sun. Have students read the text and answer the questions.
Answer Key: • It looks like a single flower, but it is made up of many small flowers. The
stigma has two parts. The stamens are short. The anthers are joined. • The daisy.
105
3. From Flower to Fruit
3. From Flower to Fruit
stigma
1
2
petal
pollen
grains
stamen
with pollen
Concept
Stages of reproduction.
stigma
Vocabulary
Blossom, cross-pollinate, fertilization,
fertilize, germinate, pollen grain,
pollination, self-pollinate, wind.
ovary
The pollen grains open
and the male sex cells
appear.
3
4
fertilization
male sex cell
Expressing Concepts
female sex cells
The wind pollinates this bulrush.
Pollination
Conjunctions: so, because
Other plants have small green flowers,
so animals do not notice them.
This happens because the wind or
animals transport the seeds.
Focus on Science
Pollination
Materials: Photos of a variety of
flowers.
Explain that pollen is a fine powder
produced in the anthers (the male
parts of the flower). Pollen contains
the male sex cells. For fertilization to
take place, these male sex cells have
to come in contact with the female
sex cells of the same or a different
flower.
Many plants, especially grasses, use
wind to transport their pollen. The
flowers of these plants often have
small green petals.
Other plants rely on animals to
transport their pollen from one
flower to another. The flowers of
these plants are usually large and
colorful, to attract the animals.
Display photos of flowers and have
students say if they are windpollinated or animal-pollinated.
106
Parts of the
ovary will turn
into fruit.
Fertilization of a Pea Plant
This lesson may be used to review
the following language:
Ask students if they (or members of
their families) are allergic to pollen.
Ask at what time of year their
sensitivity tends to increase and to
explain why (during spring and
summer, when flowers produce
pollen for fertilization).
The fertilized cells
will turn into seeds.
Questions
1. What is pollination?
2. How are plants fertilized?
3. What do the seeds do?
Plants with flowers reproduce sexually. This
happens when pollen from the stamen reaches the
pistil. Pollination is the transfer of pollen from the
male part to the female part of flowers.
Some plants self-pollinate. The pollen comes
from the stamens of the same plant. Other plants
cross-pollinate. The pollen comes from the stamen
of another plant of the same species.
The wind and certain animals can transfer pollen
from one flower to another.
• For example, the wind transports the pollen of
wheat flowers. The pollen can reach the flowers
of many different wheat plants.
• Some animals and insects, like hummingbirds
and bees, also transport pollen. When bees land
on flowers to feed, pollen sticks to their bodies.
They then carry the pollen from one flower to
another. Bees pollinate rosemary flowers,
for example.
Plants that rely on animals for pollination have
brightly-colored flowers or strong smells to attract
the animals. Other plants have small green flowers,
so animals do not notice them. The wind transports
the pollen of these plants.
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Pollination
Have students look at and describe the photo. Explain that the powder is
pollen, which contains the male sex cells. For reproduction to take place,
these sex cells have to come in contact with the female sex cells, produced
in the ovary. Plants have adapted in different ways to ensure that the male
sex cells come in contact with the female sex cells (pollination). Pollination
occurs only in plants of the same species. In some species, wind and
animals transport the pollen between plants that are far from each other.
Have students read the text and answer Question 1.
Explain that the appearance of a flower is related to its method of pollination:
flowers that rely on animals for pollination are often brightly colored or
strong smelling; wind-pollinated flowers often do not have petals and are not
immediately recognizable as flowers. Sometimes certain colors attract specific
animals, such as yellow and blue for bees, and red and yellow for birds.
Fertilization
In pairs, have students study the Fertilization of a Pea Plant diagram and
describe the process. Have them read the text and answer Questions 2 and 3.
Look
Traveling Fruit
Fertilization
Language Skills: Writing
The fruit of a dandelion is very light.
Its seed is very small. The seed is
attached to a stem with a blossom at
the top. When the wind blows, it
carries the fruit with it. For this reason,
dandelion seeds can germinate a long
way from the plants they come from.
Most plants do not have flowers throughout the
year. They flower during their reproductive season,
usually in spring. A mature flower produces sex
cells: male sex cells, or sperm, in the anthers and
female sex cells, or ovules, in the ovary.
During reproduction, a female cell unites with a
male cell. The reproductive process is as follows:
1. The anther produces a lot of pollen grains.
The pollen grains contain the male sex cells.
2. The pollen grains fall on the stigma.
3. The pollen grains open and the male sex
cells come out. The male sex cells penetrate
the pistil.
4. Fertilization occurs inside the ovary. That is where
the male and female sex cells unite.
After fertilization, the fertilized cells become seeds
and part of the ovary turns into a fruit.
The seeds fall to the ground and germinate. This
produces new plants. Some seeds germinate a long
way from the plants they come from. This happens
because the wind or animals transport the seeds.
Stages of Fertilization
Materials: Paper (1 sheet per group).
Divide the class into small groups.
Have each group copy the
Fertilization of a Pea Plant diagram
on a sheet of paper and write
captions describing each stage
around it.
a lot of fruit
a single fruit
Display students’ diagrams around
the classroom.
blossom
seed
stem
• Could the fruit be transported by
the wind without its blossom?
• Could it be transported by the wind
if the seeds were big and heavy?
Cross-Curricular Connection
Health Education:
Medicinal Plants
Activities
1
Complete the sentences.
a) Pollination is
b) The
Explain that a number of plants can
be used for medicinal purposes, such
as chamomile, aloe vera, lime,
rosemary, willow and arnica. Ask
students if they have ever taken
medication derived from a plant and,
if so, what it was, what it was for and
which plant it was derived from.
Point out that not all plants are
medicinal and that, on the contrary,
some are highly poisonous.
.
and
are involved in pollination.
c) In self-pollination, the pollen from a flower's stamen falls on the
plant.
of the
d) In cross-pollination, the pollen from a flower's stamen falls on the
of a
plant.
e) During fertilization, a
f) Fertilization takes place in the
2
sex cell unite.
of a flower.
Explain the differences between:
a) pollination and fertilization.
b) female sex cells and male sex cells.
3
sex cell and a
c) pollen and male sex cells.
d) seeds and female sex cells.
Which parts of a flower are involved in fertilization?
87
Have students look in their homes
for medicinal products derived from
plants. Ask them to present reports
on what the products contain and
what ailments they treat.
Have students do the Activities in pairs. Have each pair compare answers
with another pair. Then have several pairs report their answers to the class.
Activities
Answer Key: 1 a) the transfer of pollen from the stamen to the pistil. b) wind;
animals. c) stigma; same. d) stigma; different. e) male; female. f) ovary. 2 Sample
answers: a) Pollination is the transfer of pollen from the stamen to the pistil.
Fertilization is the union of a male and female sex cell. b) Female sex cells (ovules)
are produced in the ovary and male sex cells (sperm) are produced in the anthers.
c) Pollen contains the male sex cells. d) Seeds form after the female sex cells unite
with the male sex cells in the ovary. 3 The pistil and the stamens.
Look: Traveling Fruit
Explain that dandelions have yellow petals; after fertilization, they look
like the one pictured in the book. Have students read the text and answer
the questions.
Answer Key: • No (the blossom allows it to float in the wind). • No.
107
4. Germination and Growth
4. Germination and
Growth
Bean Germination
Concepts
Stages of reproduction. The life cycle
of plants. Seasonal changes in plants.
Vocabulary
Cross section, deciduous, evergreen,
germinate, germination, life span.
1. The root comes out.
2. The root and the stem
grow.
3. The leaves form.
Expressing Concepts
4. The root and the stem
continue growing. The
existing leaves grow.
New leaves come out.
Germination
This lesson may be used to review
the following language:
A seed produces a new plant through the process of
germination. A seed must fall to the ground and
have water to germinate.
A bean germinates in various stages. First, the
bean becomes buried in the soil. Later, a small root
grows downward. Then the stem starts to grow.
Finally, the leaves grow.
Some seeds need special conditions to germinate.
For example, some need to spend the cold
months of winter in the soil to be able to
germinate in spring.
Adverbs of sequence
First, the bean becomes buried in
the soil.
Later, a small root grows downward.
Growth
Focus on Science
Germination in Different Seeds
Questions
Materials: Different seeds (e.g., beans,
corn), blotting paper, glass jar, sand.
Have students line the inside of a
glass jar with wet blotting paper and
fill it with sand. Tell them to keep
the paper moist throughout the
experiment. Have students place
different seeds between the paper and
the glass and watch them germinate.
Ask students to measure the growth of
the seeds over a few weeks and draw
line graphs of their development.
Have students compare how the
seeds germinate: Which seed
germinates the fastest? Are there
differences in the kind or number of
leaves? Which appears first, the root or
the stem? Are all the leaves the same?
1. What is germination?
2. How does germination
happen?
3. How long do plants live?
4. How do trees change during
the year?
A plant grows gradually after germinating. It keeps
growing until it becomes an adult plant. Some
plants, like trees, keep growing throughout their lives.
The life span of plants varies a lot. In general, trees
can live for many years. Other plants, like poppies,
live for only one year.
The seasons of the year affect the life of plants.
Plants flower in spring. Their fruit and seeds grow
and mature in summer. Some plants lose their
leaves in autumn. Their branches are bare
during winter.
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Germination
Ask students what plant parts are involved in asexual reproduction
(tubers, bulbs, stolons). Clarify that seeds are produced only in sexual
reproduction. Explain that some seeds require special conditions to
germinate. The case of a mistletoe seed needs to be cracked inside a bird’s
digestive system and then fertilized by its excrement in order to germinate.
Have students study the Bean Germination diagram and read the text. Then
have them answer Questions 1 and 2 and do Activity 1.
Growth
Ask students what plants need to live (nutrients, water, suitable light, soil
and temperature).
Mention that annual plants grow from seeds and die in the same year,
biennial plants in two years and perennial plants in many years. Some
plants live much longer than the longest-living animals. For example,
there are bristlecone pine trees in the western United States that are nearly
5,000 years old.
Ask students to read the text and answer Question 3.
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Look and Compare
How Can We Measure
the Age of a Tree?
Trees throughout the Year
Trees change throughout the year. For example,
trees flower in spring. Reproduction also takes place
in spring.
The leaves on trees also change. Evergreen trees
have leaves all year long. For example, pine trees
are evergreen. Deciduous trees lose their leaves in
autumn. For example, apple trees are deciduous.
Language Skills: Speaking
We can calculate how old a tree is by
counting the rings on a cross section of
its trunk. Each ring represents one year
of growth. The rings generally vary in
color and thickness because tree
growth varies from year to year.
The longest-living plant is believed to
be a species of pine tree called the
bristlecone pine. Some bristlecone
pines are 4,850 years old. This means
that they were alive when the
Egyptians were building the pyramids.
If Trees Could Talk
Invite students to imagine that trees
are able to talk and recount all the
things they have seen in their long
lives. Divide the class into pairs and
have each pair choose a local tree.
Then have each pair write an
interview in which the tree describes
how it looked when young, how it
grew over the years and the changes it
has seen throughout its life. Have
pairs act out their interviews.
A lot of plants have lost
their leaves by winter.
Cross-Curricular Connection
Growth Rings of a Tree
• Why does the number of rings on a
trunk tell us how old the tree is?
• Which live longest, plants or
animals? Discuss.
These plants
grow new leaves
in spring.
Language Arts:
The Changing Seasons
Ask students what season it is. Have
them describe the landscape, focusing
on the stages of life of the plants.
Activities
1
Elicit observations about how the
trees change throughout the year.
Have students describe the trees
around the school and ask them
to predict what changes they will
undergo in subsequent seasons.
Remind them that not all trees lose
their leaves in autumn.
Complete the sentences.
Stages of Germination
1. A
2. The
2
is buried in the soil.
grows
3. Then, the
.
4. Finally, the
grows.
grow.
Explain how plants change throughout the year. Give examples.
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Trees throughout the Year
Explain that many plants flower in spring. The fertilized flowers produce
fruits in the summer, the fruit falls to the ground in autumn and the seeds
germinate the following spring.
Have students read the text and answer Question 4. Ask students to name
evergreen and deciduous trees (e.g., evergreen—pine, spruce, cypress;
deciduous—oak, maple, beech). In pairs, have them do Activity 2.
Activities
Answer Key: 1 1. seed. 2. root; downward. 3. stem. 4. leaves. 2 Sample answer: Apple
trees flower in spring. The fruit ripens in summer. In autumn, the fruit falls to the
ground and is eaten by animals or rots. The seeds are exposed. The seeds germinate
the following spring, producing a new plant.
Look and Compare: How Can We Measure the Age of a Tree?
In small groups, ask students to read the text and to discuss and answer the
questions. Clarify that one year’s ring comprises a dark and a light ring.
Answer Key: • Because a new ring appears every year. • In general, plants live longer.
Invite students to write poems on the
subject of the changing seasons.
Worksheet 15
Stages of Plant Reproduction
Preparation: Photocopy page 140
(1 per student).
Answer Key: 1. 4—fruits and seeds;
5—germination; 1—flowers;
3—fertilization; 2—pollination.
2. See preceding answer. 3. 1. flowers;
flowers form. 2. pollination; insects
and the wind carry pollen from one
part of the flower to another or from
one plant to another. 3. fertilization;
pollen fertilizes the ovules of the same
or another plant. 4. fruits and seeds;
fruits and seeds develop.
5. germination; new plants form.
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SOCIETY
Society/Investigate
Greenhouses
What Are Greenhouses?
Greenhouses are enclosed areas where we
grow plants. We grow plants for food in
many greenhouses. We also grow plants to
decorate the streets and our homes. A lot
of the peppers, green beans, tomatoes,
roses and tulips that we see in markets
grow in greenhouses.
Concept
Cultivation of plants.
Vocabulary
Fertilizer, greenhouse, humidity, nectar,
pollen.
We grow decorative plants
like geraniums in greenhouses.
Expressing Concepts
Cultivating Plants
In greenhouses, we can control everything that
affects plant reproduction and growth. We can
keep the temperature and humidity at optimum
levels. We can give each plant the water and
fertilizer it needs. We can also give the plants
substances to keep them healthy.
Consequently, the plants grow quickly. They
produce fruit several times a year.
This lesson may be used to review
the following language:
Could
For example, you could only buy
cucumbers in summer.
Monitoring plants in a greenhouse.
The Advantages
Growing plants in greenhouses gives us a
lot of fruit all year long. Not long ago,
each fruit had its season. For example, you
could only buy cucumbers in summer.
Now you can buy cucumbers at any time
of the year. This is because we grow them
in greenhouses.
Focus on Science
Cultivation of Plants
Discuss the fact that humans have
cultivated plants for food for
thousands of years; to learn how
to do this, ancient peoples had to
observe plants and learn about their
methods of reproduction.
Divide the class into groups. Set a
time limit and have groups make lists
of plants that humans can eat. Have
them sort the plants into those that
grow locally and those that do not.
Name different plant foods and have
students say if they are available all
year round or only at certain times
of the year.
Ask students if it is possible to
cultivate plants not native to an area
or out of season and how. Explain
that the artificially controlled
conditions of a greenhouse permit
the cultivation of a large variety of
plants all year round.
We also grow fruit in greenhouses,
like these peppers.
1
Describe the greenhouses in the photographs.
• How big are they?
• What materials are they made of?
• What plants do we grow in them?
2
What are the advantages of growing plants in greenhouses?
3
Find out about the greenhouses in your community.
What plants grow in them?
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Greenhouses
In groups, have students brainstorm answers to this question: What are the
advantages of growing plants in greenhouses? (Greenhouses provide food at
any time of the year, regardless of the environmental conditions outside.)
Have students look at and describe the photos. In pairs, have them read
the text and do the activities.
Answer Key: 1 • They are very big. • They are made of metal and glass. • Fruits,
vegetables and flowers. 2 Sample answer: We can control the conditions to make the
plants grow quickly. We can grow plants all year round. The plants produce flowers
and fruits several times a year. 3 Sample answer: geraniums, pansies, daisies, cacti,
peppers, tomatoes, strawberries.
Animal Pollination
Have students identify the animal in the illustrations. Then have individual
students describe the process of pollination orally. Elicit the names of other
animals that transport pollen (e.g., hummingbirds, bees, butterflies). Have
students do the activities.
110
INVESTIGATE
Animal Pollination
1
Look at the pictures.
1
Language Skills: Writing
2
3
4
Class Cookbook
Materials: Paper, yarn.
2
Put the sentences in the correct order. Write
them in the table.
The pollen from the stamen sticks to the
bat’s face.
The bat drinks the nectar of the cactus
flower.
The pollen on the bat’s face comes
into contact with the stigma of another
cactus flower.
The bat flies away from the flower
with a lot of pollen on its face.
HEALTH EDUCATION
Divide the class into pairs. Ask
students to write recipes for dishes
containing fruits or vegetables.
Explain that a recipe should begin
with a list of ingredients, including
the quantity of each, followed by
instructions, along with the utensils
needed, for preparing the dish.
Pollination of a Cactus Flower
1.
Bind the finished recipes together
with yarn to make a class cookbook.
Invite individual students to give
their classmates cooking classes.
2.
3.
4.
Cross-Curricular Connection
Wash Fruit before
You Eat It
Social Studies: Plant Foods
around the World
You can eat some fruit, like apples, with
the skin still on. The skin contains
nutrients too and is good for your teeth.
Before you eat fruit, wash it well to
remove dirt and other substances. These
substances can get on the skin of the
fruit while the plant is growing. It can
also get on the skin when the fruit is
transported or sold.
Materials: Reference books on history,
computer with Internet access.
Grapevine
• Why should we wash fruit before eating it?
• Make a list of fruits that we can eat with the skin still on. How do you normally eat fruit?
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Answer Key: 2 1. The bat drinks the nectar of the cactus flower. 2. The pollen from
the stamen sticks to the bat’s face. 3. The bat flies away from the flower with a lot of
pollen on its face. 4. The pollen on the bat’s face comes into contact with the stigma
of another cactus flower.
Wash Fruit before You Eat It
Ask students where the fruit they eat at home comes from. Ask if they
grow fruits or vegetables at home. Invite students to talk about their
favorite fruits and vegetables.
In pairs, have students read the text and answer the questions.
Answer Key: • To remove dirt and other substances, which may make us sick. • Sample
answer: Apples, pears, peaches, plums, grapes. I normally eat fruit with the skin on.
Explain that although some plants
are now cultivated virtually all over
the world, this was not always the
case. In groups, ask students to look
for information about fruits and
vegetables (e.g., sugarcane, corn,
tomatoes, potatoes, pineapples)
brought from one part of the world
to be cultivated in another, such as
from Europe to the Americas. Have
each group prepare a presentation on
a fruit or vegetable, including maps,
illustrations, fruits and vegetables.
Worksheet 16
Plants through the Seasons
Preparation: Photocopy page 141
(1 per student).
Answer Key: 1. 1. Spring. 2. Flowers
attract insects and other animals.
3. Fruit develops from the ovary and
seeds from the fertilized ovules.
2. 1—It has flowers; Spring.
2—It has fruit and leaves; Summer.
4—It does not have any leaves; Winter.
3—Its leaves are falling; Autumn.
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Test Your Knowledge
Test Your Knowledge
1
Copy and complete the diagram.
Plant Reproduction
Reinforcement Activities
involves
Sexual Reproduction in Animals
and Plants
involves
leaves
these produce
In groups, ask students to explain
the similarities and differences
between fertilization in animals and
plants. Encourage them to use
illustrations to aid their explanations.
for example
sex cells
bulbs
2
female
Complete and answer.
a) Copy the pictures. Label the parts.
b) Write these sentences in the correct boxes:
• The pollen grains in the stamen fall on the stigma of the pistil.
• The female sex cells and the male sex cells unite inside the pistil.
• The pollen grains open. The male sex cells appear and move to the inside
of the pistil.
c) What is this process called? What is the result?
Sexual and Asexual Reproduction
Ask students to find out how these
plants reproduce: potato, apple tree,
rose bush, onion, pepper, strawberry.
Fruits and Seeds
1
Show photos of different fruits and
ask these questions: What plant does
it come from? How many seeds does
each fruit have? What type of seed coat
does it have?
2
3
Seeds
Ask students to write an explanation,
including diagrams, in answer to the
question How do plants make seeds?
3
Garden Centers
• Formation of the fruit and seeds.
• Fertilization.
Take students to a garden center and
have them find out how different
plant species are propagated.
Assessment 8
Flowering Plants
Preparation: Photocopy page 113
(1 per student).
Answer Key: 1. 1. Petals protect other
parts of the flower and attract animals.
2. The stigma is where the pollen from
another flower is deposited. 3. The
ovary produces the female sex cells
(ovules). 4. The anthers produce the
male sex cells (pollen). 5. The sepals
protect the flower before it opens.
2. 1. When pollen falls on the stigma of
the same plant. 2. When pollen falls on
the stigma of another plant. 3. When
wind carries pollen from the stamen of
one plant to the stigma of another.
4. When animals carry pollen from the
stamen of one plant to the stigma of
another. 5. When a male sex cell and a
female sex cell unite in the ovary.
112
Put these stages in the correct order. Complete the diagram.
• Development of the plant.
• Appearance of the flowers.
1.
2. Pollination.
3.
6.
5. Germination.
4.
92
Have students do the activities in pairs or groups. Encourage them to look
back in the unit for information they do not remember.
Answer Key: 1 asexual; involves stem, leaves; for example: bulbs, tubers, stolons.
sexual; involves flowers; these produce sex cells; female, male. 2 Answers given clockwise
from top left: a) 1. petal; pollen grains; style. 2. female sex cells; pollen grain; male sex
cell; ovary. 3. female sex cell; ovary; fertilized cell. b) 1. The pollen grains in the
stamen fall on the stigma of the pistil. 2. The pollen grains open. The male sex cells
appear and move to the inside of the pistil. 3. The female sex cells and the male sex
cells unite inside the pistil. c) Pollination. The result of pollination is the production
of fertilized cells that will turn into seeds. 3 1. Appearance of the flowers.
2. Pollination. 3. Fertilization. 4. Formation of the fruit and seeds. 5. Germination.
6. Development of the plant.
Assessment 8
Name:
Date:
Flowering Plants
1. Label the parts of the flower with the words in the box and
describe their functions. (5 points)
petals
stigma
sepals
anthers
ovary
1.
2.
3.
4.
5.
1.
2.
3.
4.
5.
2. Define the terms. (5 points)
1. Self-pollination:
2. Cross-pollination:
3. Wind pollination:
4. Pollination by animals:
5. Fertilization:
PHOTOCOPIABLE
Science 5 © 2003 Santillana Educación, S. L./Richmond Publishing
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