Download Plant Reproduction and Response

Name
Class
Date
Plant Reproduction
and Response
Growth, Development, and Reproduction
Q: How do changes in the environment affect the reproduction,
development, and growth of plants?
WHAT I KNOW
24.1 How do
flowering plants
reproduce?
24.2 How
are fruits and
seeds important
adaptations for
plants?
24.3 How do
plants respond to
their environments?
24.4 In what
ways do humans
depend on plants?
WHAT I LEARNED
SAMPLE ANSWER:
Flowering
plants reproduce by making
seeds in flowers.
Flowering plants
produce male and female
gametophytes in flowers.
Pollen grains transfer sperm
to the stigma of a flower.
Double fertilization in an
ovule produces a zygote and
endosperm. The ovule becomes
a seed.
SAMPLE ANSWER:
Fruits protect
seeds, and seeds grow into
new plants.
SAMPLE ANSWER:
SAMPLE ANSWER:
Plants
respond to light and other
environmental factors such
as temperature.
SAMPLE ANSWER:
SAMPLE ANSWER:
SAMPLE ANSWER:
Humans depend
on plants for food.
SAMPLE ANSWER:
Fruits are
adaptations for seed dispersal.
Seeds enable plant embryos
to be transported over long
distances and remain dormant
until the environment is
favorable for growth.
Plants make
hormones that affect cell
growth. Some hormones cause
stems to bend toward or away
from light or gravity. Others
regulate the growth of buds,
fruits, flowers, and seeds or
stimulate fruit ripening.
In addition to
food, plants provide humans
with wood for building and
fuel, fibers for making paper
and cloth, and medicines.
Chapter 24 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
377
Name
Class
Date
24.1 Reproduction in Flowering Plants
Lesson Objectives
Identify the functions of various structures of a flower.
Explain how fertilization differs between angiosperms and other plants.
Describe vegetative reproduction.
Lesson Summary
The Structure of Flowers Four different kinds of specialized leaves form flowers.
▶ Sepals form the outermost circle of flower parts. They protect a flower bud.
▶ Petals form a ring just inside the sepals. Some are brightly colored, which attracts
pollinators.
▶ Stamens are the male reproductive structures and form a ring inside of the petals. Pollen
is produced in an anther, which is the sac at the tip of a stamen. Each pollen grain
contains a male gametophyte.
▶ Carpels are the female reproductive structures at the center of flowers. The female
gametophytes develop inside the ovules that form in a carpel’s ovary.
• The sticky tip of a carpel, called the stigma, captures pollen.
• A pistil is a structure that is made up of one or more carpels.
The Angiosperm Life Cycle The life cycle involves alternation of generations. Meiosis in
stamens and carpels produces haploid cells (spores) that develop into gametophytes.
▶ The haploid cells in a stamen’s anther undergo mitosis and form pollen grains, the male
gametophytes, that contain 2 sperm nuclei.
▶ A haploid cell in each ovule of a carpel undergoes mitosis to produce an embryo sac, or
female gametophyte, which contains 8 haploid nuclei. One of these nuclei becomes the egg.
▶ Pollen grains are transported to the stigmas of carpels during pollination.
▶ Both sperm nuclei fuse with nuclei in the embryo sac in a process called double
fertilization. One sperm fuses with the egg to form a diploid (2N) zygote. The other
sperm fuses with 2 other nuclei to form the triploid (3N) endosperm.
Vegetative Reproduction Asexual reproduction is common in plants.
▶ Vegetative reproduction leads to offspring that are identical to the parent. The offspring
develop by mitotic cell division of cells in stems, leaves, and roots.
▶ Horticulturists use vegetative reproduction to propagate (grow) many identical plants.
Making cuttings of stems and roots is one example. Grafting involves attaching a bud or a
stem of one woody plant to the stems of another.
Lesson 24.1 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
378
Name
Class
Date
The Structure of Flowers
For Questions 1–10, match the floral part with its description.
Description
Floral Part
B
1. anthers
A. Stalk with a stigma at the top
F
2. carpels
B. Structures that produce male gametophytes
E
3. filament
C. Structure that contains one or more ovules
C
4. ovary
D. Outermost circle of green floral parts
I
5. petals
E. Long, thin structure that supports an anther
G
6. pollen
F. Floral parts that produce female gametophytes
D
7. sepals
G. Yellowish dust that contains male gametophytes
H
8. stamen
H. Male structure with an anther and a filament
J
9. stigma
I. Brightly colored parts just inside the sepals
A
J. Sticky, top portion of style
10. style
11. Complete the illustration by labeling the parts of the flower indicated.
anther
stigma
filament
style
petal
ovary
ovule
sepal
The Angiosperm Life Cycle
For Questions 12–15, complete each statement by writing the correct word or words.
12. The body of an adult plant with flowers is the
life cycle.
sporophyte
generation of the plant’s
13. The gametophytes of angiosperms have cells with nuclei that have the
number of chromosomes.
haploid
Lesson 24.1 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
379
Name
Class
14. A male
15. A(n)
gametophyte
ovule
Date
of an angiosperm is a pollen grain.
contains a female gametophyte of an angiosperm.
For Questions 16–20, write True if the statement is true. If the statement is false, change the
underlined word or words to make the statement true.
stigma
16. In pollination, pollen grains are transferred to the ovary of a flower.
two
17. A pollen tube delivers one sperm to an ovule.
True
18. The fertilized egg in an ovule becomes the zygote of a new sporophyte.
True
19. Triploid tissue, called endosperm, forms in double fertilization.
ovule
20. A fertilized embryo sac then develops into a seed.
Vegetative Reproduction
21. What is vegetative reproduction in plants?
It is the production of offspring from one parent that results from mitotic cell division
in nonreproductive parts such as leaves, stems, and roots.
22. Give an advantage and a disadvantage of vegetative reproduction to plants.
An advantage is that it allows well-adapted individuals to rapidly increase in
numbers. A disadvantage is that it does not result in offspring with new
combinations of genetic traits.
23. Complete the table to summarize asexual reproduction in plants.
Vegetative Reproduction in Plants
Reproductive Method
Vegetative Parts Involved
Example
Stolons
Aboveground stems
SAMPLE ANSWER:
Strawberries
Tubers
Underground stems
SAMPLE ANSWER:
Potatoes
Grafts
Stem pieces, buds
SAMPLE ANSWER:
Lemon bud grafted
onto an orange tree
24. How might a long period of rainy weather affect reproduction in wind-pollinated plants?
SAMPLE ANSWER:
A long period of rainy weather may prevent wind-pollinated plants from
being pollinated and developing fruits and seeds. Pollen floats on the wind; however,
if it were wet, the pollen would fall to the ground and never reach the stigmas of the
plants. Without pollination, there will be no fertilization and no seeds produced.
Lesson 24.1 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
380
Name
Class
Date
24.2 Fruits and Seeds
Lesson Objectives
Describe the development of seeds and fruits.
Explain how seeds are dispersed.
List the factors that influence the dormancy and germination of seeds.
Lesson Summary
Seed and Fruit Development Seeds develop in the fruit of angiosperms.
▶ A seed protects and provides nourishment for a plant embryo.
▶ An ovary matures into a fruit as an embryo develops within each of its seeds. Some fruits
are fleshy, and others are dry. Many foods are fruits.
Seed Dispersal Fruits are adaptations for seed dispersal that have been favored by natural
selection.
▶ Animals disperse seeds for many plants that make edible fruits or fruits that cling to
animal bodies.
▶ Wind and water disperse seeds for plants that make fruits with adaptations for gliding on
the wind or floating on water.
Seed Dormancy and Germination Some seeds sprout right away, and others lie dormant for a period of time.
▶ In a period of dormancy, the embryo of a seed is alive but not growing.
▶ Germination is the resumption of growth by the embryo. Seeds absorb water before
germinating. The water causes tissues in a seed to swell, causing the seed coat to crack.
The embryonic root emerges first.
▶ Monocots and dicots have different patterns of germination.
▶ Dormancy helps the embryos in seeds survive until the environment is favorable for plant
growth.
Seed and Fruit Development
For Questions 1–6, complete each statement by writing the correct word or words.
1. The function of a seed is to nourish and
2. After fertilization,
3. A fruit is a matured
nutrients
ovary
protect
a plant embryo.
flow into the flower to support the growing embryo.
of a flower.
4. Fruits are adaptations for spreading (dispersing) seeds.
5. Peas, corn, green beans, tomatoes, and rice are all examples of the
angiosperms.
6. In a peanut, the
shell
is the fruit and the nut is the
fruits
seed
Lesson 24.2 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
381
of
.
Name
Class
Date
Seed Dispersal
For Questions 7–11, write the letter of the correct answer on the line at the left.
B
7. Which tissue formed in plant reproduction nourishes the embryo?
A. nectar
C. ovary wall
B. endosperm
D. seed coat
D
8. In evolutionary terms, seed dispersal is important because it
A. allows plants to produce more offspring.
B. keeps the number of plants in an area high.
C. helps plants form new communities.
D. reduces competition with parent plants.
A
9. Seeds encased in fleshy, nutritious fruits are usually dispersed by
A. animals.
C. water.
B. gravity.
D. wind.
C
10. Which fruit would be adapted for dispersal by water?
A. a dry fruit with feathery branches
B. a greenish fruit with a sticky surface
C. a large, lightweight fruit with a thick, waxy covering
D. a small, round fruit with a sweet, jellylike covering
C
11. Which is an adaptation of a fruit for dispersal by wind?
A. a tough, hard seed coat
B. a ring of fleshy projections
C. a pair of papery wings
D. a hollow, air-filled center
Seed Dormancy and Germination
12. Complete the flowchart to summarize the process of seed germination.
Dormant
Seed
Seed absorbs
water
Seed coat
cracks open
–Young root
and shoot
emerge
Plant
Seedling
For Questions 13–20, write True if the statement is true. If the statement is false, change the
underlined word or words to make the statement true.
True
sheath
True
13. In most monocots, the cotyledon remains underground.
14. In monocots, a cotyledon protects the young shoot as it emerges.
15. The hook of the new shoot of a germinating dicot protects the new
leaves from injury by the soil.
Lesson 24.2 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
382
Name
Class
True
16. The primary root is the first root of a new plant.
germinate
17. Dormancy enables seeds to live under ideal growing conditions.
spring
21.
Date
18. The seeds of most plants in temperate regions germinate in the fall.
True
19. For many seeds, a long period of cold is required before dormancy can
end.
fire
20. The cones of some pine trees must be exposed to light in order to
release their seeds.
Complete the illustration comparing seed germination in corn
(monocot) and a bean (dicot). Under each drawing, identify the kind of plant that is
shown, and make a sketch of the missing stage for each in the appropriate circle.
For the monocot, students should draw
the seed underground with a primary
root and young shoot emerging. For
the dicot, students should draw the
seed underground with a primary root
and a young hooked shoot emerging.
It should also have cotyledons.
Corn (monocot)
Bean (dicot)
22. Lupines are flowering plants that make seeds with a thick, hard seed coat. Seeds collected
from wild lupines are difficult to grow. What could be the cause of this difficulty? How
might a hard seed coat be an adaptation that helps lupines survive?
SAMPLE ANSWER:
A hard seed coat makes it difficult for a seed to take in water,
which is the first step in seed germination. This would be an adaptation for
surviving the passage through an animal’s digestive tract, or for surviving
extremely low temperatures.
Lesson 24.2 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
383