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Lesson 2 | Plant Responses
Student Labs and Activities
Page
Appropriate For:
Launch Lab
25
all students
Content Vocabulary ELL
26
all students
Lesson Outline ELL
27
all students
MiniLab
29
all students
Content Practice A
30
AL
AL
AL
Content Practice B
31
AL
OL
BL
Math Skills
32
all students
School to Home
33
all students
Key Concept Builders
34
Enrichment
38
Challenge
39
Skill Practice
40
AL
AL
AL
all students
AL
AL
BL
all students
Assessment
Lesson Quiz A
42
AL
AL
AL
Lesson Quiz B
43
AL
OL
BL
Teacher Support
Answers (with Lesson Outlines)
OL On Level
BL Beyond Level
ELL English-Language Learner
Teacher evaluation will determine which activities to use or modify to meet any ELL student’s proficiency level.
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Plant Processes and Reproduction
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
AL Approaching Level
T4
Name
Date
Launch Lab
Class
LESSON 2: 15 minutes
How do plants respond to stimuli?
Photosynthesis in plants requires light energy. How do plants respond to light in their
environment?
Procedure
1. Read and complete a lab safety form.
2. Choose a pot of young radish
seedlings.
3. Place toothpicks parallel to a few
of the seedlings in the pot in the
direction of growth.
4. Place the pot near a light source,
such as a gooseneck lamp or next to a
window. The light source should be
to one side of the pot, not directly
above the plants.
5. Check the position of the seedlings
in relation to the toothpicks after
30 minutes. Record your observations
in the Data and Observations section
below.
6. Observe the seedlings after two or
more hours. Record your observations.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Data and Observations
Think About This
1. What happened to the position of the seedlings after the first 30 minutes? How could
you tell?
2. What happened to the position of the seedlings after an hour or two?
3.
Key Concept Why do you think the position of the seedlings changed?
Plant Processes and Reproduction
25
Name
Date
Class
Content Vocabulary
LESSON 2
Plant Responses
Directions: On each line, write the term from the word bank that correctly replaces the underlined words in each
sentence. NOTE: You may need to change a term to its plural form.
photoperiodism
plant hormone
stimulus
tropism
1. Plants may respond to a change in the environment by
growing toward it or away from it.
2. Seedlings bending toward light and roots curving away
from light are examples of plant growth toward or away
from environmental changes.
3. Due to a response to the number of hours of darkness in
their environment, carnations only flower in the summer,
when the number of daylight hours is greater than the
number of hours of darkness.
4. Auxins, ethylene, gibberellins, and cytokinins are
substances that act as chemical messengers within plants.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
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Plant Processes and Reproduction
Name
Date
Class
Lesson Outline
LESSON 2
Plant Responses
A. Stimuli and Plant Responses
1.
are any changes in an environment that cause
organisms to respond.
2. A plant will respond to
by growing toward it.
3. When stimulated by an insect’s
, the two sides of
a Venus flytrap snap shut immediately, trapping the insect inside.
B. Environmental Stimuli
1. Plants responses to different environmental stimuli include
, touch, and
2. A(n)
.
is a response that results in plant growth toward
or away from a stimulus.
3. The growth of a plant toward or away from light is called
a(n)
.
a. Leaves and
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
b.
tend to grow in the direction of light.
generally grow away from light.
4. The response of a plant to touch is called a(n)
a. Structures that respond to touch, called
.
, can wrap
around or cling to objects.
b. When
, the leaves of Mimosa pudica quickly droop or
fold up.
5. The response of a plant to gravity is called
a.
.
grow away from gravity.
b. Roots grow
gravity.
6. Some plants flower in response to the amount of
they
are exposed to.
a.
is a plant’s response to the number of hours of
darkness in its environment.
b. Plants that flower when exposed to less than 10–12 hours of darkness are called
plants.
Plant Processes and Reproduction
27
Name
Date
Class
Lesson Outline continued
c. Short-day plants require 12 or more hours of
for
flowering to begin.
d.
plants flower when they reach maturity and the
environmental conditions are right.
C. Chemical Stimuli
1.
are substances that act as chemical messengers within
plants.
2. Hormones are called
because they are usually produced
at one part of a plant and affect another part of that plant.
3.
generally cause increased plant growth.
4.
helps stimulate the ripening of fruit.
5.
increase the rate of cell division and cell elongation in
stems and leaves.
6.
increase the rate of cell division in some plants and
slow the aging process of flowers and fruits.
D. Summary of Plant Hormones
1. Plants produce many different
.
plant
.
E. Humans and Plant Responses
1. Humans make plants more
2. Some crop plants are now easier to
using plant hormones.
because humans
understand how they respond to hormones.
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Plant Processes and Reproduction
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
2. Often, two or more plant hormones interact and produce a
Name
Date
MiniLab
Class
LESSON 2: 20 minutes
When will plants flower?
Did you ever think plants could have strategies so that they can germinate, live, grow,
reproduce, and continue their species? Photoperiodism is one such strategy.
Procedure
1. In your Science Journal, copy the table
shown in your textbook to classify
plants based on their photoperiodisms.
2. Choose 8–10 pictures of flowers.
Record their names in your table. Use
the clues on the back of each photo to
determine the correct photoperiodism
of each plant.
Analyze and Conclude
1. Interpret Data Based on your table, which plants would flower during the summer?
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
2. Explain why some plants flower at the same time every year.
3. Infer what might happen if artificial light was put on short-day plants for an hour or
two at night.
4.
Key Concept Why would photoperiodism be an important strategy for flowering
plants?
Plant Processes and Reproduction
29
Name
Date
Class
Content Practice A
LESSON 2
Plant Responses
Directions: Circle the term or phrase that correctly completes each sentence.
1. Light, touch, or gravity that causes plant growth toward or away from a stimulus is a
(chemical hormone, tropism).
2. A plant’s tropism to light is called (phototropism, gravitropism).
3. Bending toward the light is a (positive, negative) tropism.
4. If a planter is turned so the plant bends away from the light, the plant will gradually
(bend lower, straighten).
5. The plant’s stems (will, will not) continue to grow upward if the plant is placed in
the dark.
6. Roots that grow (toward, away from) the Sun help anchor the plant in the soil.
8. A higher level of a plant hormone called (gibberellins, auxin) on the dark side of the
plant causes plant cells found there to grow longer.
9. When plant cells on the dark side of a plant grow longer, the plant (bends, dies).
30
Plant Processes and Reproduction
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
7. Some plants respond to touch. This is called (thigmotropism, photoperiodism).
Name
Date
Class
Content Practice B
LESSON 2
Plant Responses
Directions: On each blank line, write the term from the word bank that correctly completes each sentence.
Some terms may be used more than once or not at all.
auxins
chemical
day-neutral
environmental
ethylene
gibberellins
gravitropism
hormones
interact
long-day
negative
photoperiodism
productive
response
roots
stimuli
thigmotropism
tropism
Any changes in an environment that cause organisms to respond are considered
(1.)
. A plant’s (2.)
to stimuli could
be slow or rapid, but all plants respond to (3.)
.
There are two main types of stimuli: (4.)
(5.)
stimuli and
stimuli. A positive (6.)
identifies a plants response that results in growth toward a stimulus. There are three
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
types of tropisms: phototropism, (7.)
(8.)
, and
. Another type of response, (9.)
,
describes a plant’s response to hours of darkness. This response is seen in flowering plants.
Carnations, for example, are (10.)
(11.)
plants, and roses are
plants.
Chemicals produced by the plant, called (12.)
, are also
called messengers because they are produced at one part of the plant and affect another
part. Four examples of plant hormones are (13.)
(14.)
,
, (15.)
, and cytokinins.
(16.)
assist a plant’s response to light, and
(17.)
help fruit ripen.
Plants produce many different hormones. Often two or more hormones
(18.)
to make plants more (19.)
. Scientists study the interaction of hormones to find ways
. Larger plants, faster ripening fruit,
and stronger and longer (20.)
are just a few of the changes
brought about by applying additional hormones to plants.
Plant Processes and Reproduction
31
Name
Date
Class
Math Skills
LESSON 2
Use Percentages
Percentages are used to compare a partial amount to a whole amount. A whole amount is
equal to 100%. To calculate percentage, multiply a ratio by 100 and add the percent sign
1 is equal to 0.25, which is 25%.
(%). For example, __
4
To calculate percentage change, first subtract the final amount from the original amount.
Then divide by the original amount and convert to a percentage.
A plant grows 1 mm per day when given pure water. When given water with gibberellins
added, the plant grows 4 mm per day. What is the percentage increase in growth?
Step 1 Subtract the original value from the final value.
4 mm - 1 mm = 3 mm
Step 2 Then set up a ratio. Divide the result of Step 1 by the original amount.
3 mm
_____
= 3 mm
1 mm
Step 3 Multiply by 100 and add a percent sign.
3 × 100 = 300%
Practice
1. A plant grows 3 mm per day when
2. A plant grows 5 mm per day when
given pure water. When given water
with gibberellins added, the plant
grows 10 mm per day. What is the
percentage increase in growth?
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seedlings grew to 6 cm in 3 days. With
chemical stimulus, sunflower seedlings
grew to 10 cm in 3 days. What was the
percentage increase in growth?
4. Without chemical stimulus, pea
seedlings grew to 1.2 cm in 1 day. With
chemical stimulus, pea seedlings grew
to 2.3 cm in 1 day. What was the
percentage increase in growth?
Plant Processes and Reproduction
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
given pure water. When given water
with gibberellins added, the plant
grows 4 mm per day. What is the
percentage increase in growth?
3. Without chemical stimulus, sunflower
Name
Date
Class
School to Home
LESSON 2
Plant Responses
Directions: Use your textbook to complete the table.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Plant Stimulus
Description of Response
Environmental Stimulus or
Chemical Stimulus
1. Auxin
a.
b.
2. Cytokinins
a.
b.
3. Ethylene
a.
b.
4. Gibberellins
a.
b.
5. Gravitropism
a.
b.
6. Photoperiodism
a.
b.
7. Phototropism
a.
b.
8. Thigmotropism
a.
b.
Plant Processes and Reproduction
33
Name
Date
Class
Key Concept Builder
LESSON 2
Plant Responses
Key Concept How do plants respond to environmental stimuli?
Directions: On each blank, write the term or phrase that correctly completes each sentence.
1. Changes in the environment that cause an organism to respond are
called
.
2. Environmental stimuli include
,
, and
.
3. When a response results in plant growth toward or away from a stimulus, the response
is called a(n)
4. A(n)
.
tropism occurs when the growth is toward the stimulus.
5. Growth of a plant toward or away from light is called
6.
.
is a plant’s response to gravity.
7. Another response,
, describes a plant’s response to touch.
8. Vines that coil around a nearby plant are demonstrating
.
9. Flowering plants show a response to darkness called
.
hours of darkness
to flower.
11. A(n)
plant does not seem to be affected by the number of
hours of darkness.
12. Plants that flower in early summer but not in late fall are called
plants.
13. Stems grow away from gravity, and roots grow toward gravity. This
describes
.
14. A stem grows
even when there is no light.
15. Roots growing away from a source of light are examples of
tropism.
16. Leaves tend to grow in the direction of
.
17. The dropping of leaves in the fall is the tree’s response to
stimuli.
18. The tendrils of vines coil as a response to
34
.
Plant Processes and Reproduction
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
10. A short-day plant must have more than
Name
Date
Key Concept Builder
Class
LESSON 2
Plant Responses
Key Concept How do plants respond to environmental stimuli?
Directions: Answer each question in the space provided.
Environmental Stimuli
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
This is the cause.
What is the effect?
1. Sunlight enters a room and
shines on a potted plant near
the window.
1.
2. A seed lands on the soil and
starts to grow.
2.
3. The tendril of a vine touches
the branch of a nearby shrub.
3.
4. Day-neutral plants reach
maturity, and environmental
conditions are right.
4.
5. Short-day plants receive less
than 12 hours of darkness.
5.
6. A potted plant falls on its side
and goes unnoticed.
6.
7. A plant that leans toward the
window is moved outside.
7.
8. A fly lands inside the leaves of
a Venus flytrap.
8.
9. The roots of a plant are pulled
out of the wet soil and left to
lay on the ground.
9.
10. A vine touches the side of a
building.
Plant Processes and Reproduction
What is this response
called?
10.
35
Name
Date
Class
Key Concept Builder
LESSON 2
Plant Responses
Key Concept How do plants respond to chemical stimuli?
Directions: Label the diagram by writing the three responses plants have to each plant hormone.
1. Auxins
2. Ethylene
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
3. Gibberellins
4. Cytokinins
Directions: Answer the question on the lines provided.
5. Why are plant hormones called messengers?
36
Plant Processes and Reproduction
Name
Date
Class
Key Concept Builder
LESSON 2
Plant Responses
Key Concept How do plants respond to chemical stimuli?
Directions: Respond to each statement in the space provided.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
List four plant hormones.
Explain how the plant
responds to the plant
hormone.
Describe how the response
benefits the plant.
1. Summarize how plant hormones benefit plants.
2. Explain three ways you are dependent on plants.
3. Describe how humans use plant hormones to make plants more productive.
Plant Processes and Reproduction
37
Name
Date
Class
Enrichment
LESSON 2
Forcing Flowers
match could cause the plants to fail to
bloom and could cost the grower an entire
season’s crop.
Long-day plants are grown in similar,
but warmed environments to induce them
to bloom in winter, but they are treated to
short periods of light during the night
hours. Flashes of light are enough to fool
the plant into responding as if it were
having a long day. By understanding
photoperiodism and controlling periods of
light, flower growers keep out-of-season
flowers ready to buy at any time.
Controlled-Light Environments
Genetic Engineering
A short-day plant, such as a
chrysanthemum or mum for short, are
so-called because when days are short, nights
are long, and it is really the long night that
is critical. Mums have a critical night length
for flowering from between 14 to 16 hours.
Professional growers house these plants in
vast greenhouses in row after row. To
lengthen the night and simulate the mums’
natural blooming time, the houses are
cooled to approximately 20°C (68°F) and are
sealed from any light from afternoon to the
next morning. No one is allowed in or out
without night-vision goggles, and they must
enter an anteroom and close the door before
they enter the greenhouse. Even striking a
Some researchers are investigating a
specific gene that controls flowering
periods. Introducing a certain gene to a
plant’s leaves can cause it to flower at a
time when it normally would not. The
implication of this kind of genetic
manipulation is that plants would not be
dependent upon seasonal changes in night
length to reproduce. Flower growers would
not need expensive greenhouses to force
blooms out of season. Benefits to farmers
and the world’s food supply are enormous.
The growing season for food crops with
photoperiods, such as spinach, rice, and
strawberries could be expanded to most of
the year.
Applying Critical-Thinking Skills
Directions: Respond to each statement.
1. Explain a benefit of having certain popular flowers available all year long.
2. Infer what effect expanding a crop’s growing season would have on the world’s food
supplies.
3. Describe two very different ways that certain plants can be manipulated to produce
out-of-season flowers.
38
Plant Processes and Reproduction
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
A plant’s response to changes in the
length of days and nights is called
photoperiodism. A plant that blooms only in
the summer is a long-day, short-night plant
because in summer, in temperate zones, the
days are longest and the nights are shortest
of any other season.
Carnations, chrysanthemums, and
poinsettias are available all year long. There
are basically two ways that professional
flower growers manipulate flowering in
plants—controlled-light environments and
genetic engineering.
Name
Date
Challenge
Class
LESSON 2
Plant Growth Manipulation
Below is a list of common plant hormones and their typical functions.
Plant Hormone and Typical Function
Hormone
Function
Auxins
promotes cell growth, root formation on stem and leaf cuttings, stem tip growth
dominance, suppression of lateral buds, and increased number of fruits; concentrated
in stem tips and young leaves
Ethylene
promotes ripening of fruit, flowering in some tropical fruits, and dropping of leaves;
concentrated in fruits, flowers, leaves, and roots
Gibberellins
promotes elongation growth, germination, seedling growth, increased size of fruit,
and flowering; concentrated in immature seeds; found in all parts of a plant
Apply Knowledge to New Situations
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Suppose you are a horticulturist who needs to produce certain effects in some plants you
want to sell. Examine the table of hormones and their typical effects to help determine your
course of action in each situation below. Draw pictures as needed to explain.
Situation
Answer to Question
Drawing
1. You have requests from buyers
for a plant that can be grown
only from leaf cuttings. You can
sell the plants if they are fully
rooted and potted for the new
customers. What can you do to
speed up the development of
roots in your leaf cuttings?
2. A pear tree you ordered for
your plant nursery won’t sell
because the fruits are so small.
What can you do to assist this
tree in producing large, robust
fruit?
Plant Processes and Reproduction
39
Name
Date
Skill Practice
Manipulate Variables
Class
LESSON 2: 20 minutes
What happens to seeds if you change the intensity of light?
Seeds require light, water, gases, and soil to germinate, grow into seedlings, and then grow
into mature plants. Different types of seeds require different amounts of each of these
factors. What happens if one of these factors is out of balance?
Materials
plastic tub
potting soil
fast-growing grass seeds
sun shields
light source
metric ruler
mister bottle with water
Safety
Learn It
In any experiment, it is important to keep everything the same except for the item you are
testing. The one factor you change, or manipulate, is called the independent variable.
Your experiment should also have a control. The control is an individual instance or
experimental subject for which the independent variable is not changed.
Try It
1. Read and complete a lab safety form.
about 1–2 cm from the top. Spread the grass seeds evenly across the soil. Cover the
seeds with a thin layer of soil.
3. Obtain the precut shields of vellum, plastic needlepoint grid, and cardboard. These will
be used to change the intensity of light shining on the soil.
4. Cover the soil with the shields by laying them next to each other. Leave one section of
soil uncovered.
5. Place the tub on a windowsill or under a growing light.
6. Keep the soil damp, not wet, with a mister. Water gently so the seeds stay in position.
7. Design a table to record observations in the Data and Observations section at the top of
the next page. Include columns for day, growth pattern, height, and random sampling
counts. Begin observations when seedlings first emerge. Observe seedlings for 3–5 days.
40
Plant Processes and Reproduction
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
2. Fill the plastic tub with potting soil. Water the soil and then add more soil. Level it to
Name
Date
Class
Skill Practice continued
Data and Observations
Apply It
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
8. Identify the variables and the controls used in this investigation.
9. Analyze the data you collected through your observations. Which light intensity
appeared to bring about the fullest, tallest growth?
10. Draw Conclusions What would happen if you put one section of seeds in total
darkness? Would it germinate? If you changed the light intensity immediately after the
seeds germinated, would it survive?
11.
Key Concept Does the amount of light affect the germination and growth of
grass seeds? Explain.
Plant Processes and Reproduction
41