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Name:___________________ Grade 9 ( )
Date: ___________________ worksheet # 9 Ch. 22, L: 22.3

Lesson 22.3 Summary

Flowering plants are the most abundant organisms in the plant kingdom.

Angiosperms

Angiosperms produce flowers, which contain ovaries that surround and protect the seeds. After
fertilization, ovaries within flowers develop into fruits.

Angiosperm Classification Flowering plants were previously classified by the number of seed
leaves, or cotyledons (kaht uh leed uns), in their embryos. They had one (monocot) or two
(dicot). Today, monocots form a single group, but dicots fall into different categories.

Angiosperm Diversity Angiosperms vary by the number of seed leaves, the strength and
composition of their stems, and the number of growing seasons they live.

Monocots and Dicots Angiosperms are called either monocots or dicots based on the number of
seed leaves they produce.

Woody and Herbaceous Plants Woody plants are made primarily of cells with thick cell walls
that support the plant body. Herbaceous (hur bay shus) plants do not produce true wood.

Annuals, Biennials, and Perennials The life span of plants is determined by genetic and
environmental factors.

Flower Structure

Flowers are an evolutionary advantage to plants because they attract animals such as bees,
moths, or hummingbirds. These animals—drawn by the color, scent, or even the shape of the
flower—carry pollen with them as they leave. Because these animals go directly from flower to
flower, they can carry pollen to the next flower they visit. This means of pollination is much
more efficient than the wind pollination of most gymnosperms. Flowers are reproductive organs
that have four specialized parts: sepals, petals, stamens, and carpels.

Grade 9/Term 3/Biology 1

Sepals The outermost portion of a flower consists of modified leaves called sepals. They enclose
the bud before it opens and protect the flower as it develops.

Petals, which are often brightly colored, are found just inside the sepals. The colors and shapes
of petals help to attract insects and other pollinators to the flower. Petals generally fall off a
flower within several days. Losing petals also helps the plant reproduce.

Stamens and Carpels Inside the ring of petals are organs that produce male and female
gametophytes. The stamens are the male parts of the flower. Each stamen consists of a
stalk called a filament with an anther at its tip. Anthers are the structures in which pollen grains
—the male gametophytes—are produced. The innermost floral parts are the carpels, which
produce female gametophytes and, later, seeds. The carpels are fused into a broad base, forming
an ovary where the female gametophytes are produced. The diameter of the carpel narrows into a
stalk called the style. At the top of the style

is a sticky or feathery portion known as the stigma, which is specialized to capture pollen.
Botanists sometimes call a single carpel or several fused carpels a pistil.

Variety in Flowers Flowers vary greatly in shape, color, and size. While most flowering plants
produce both male and female gametophytes, in some species the male and female gametophytes
are produced on different plants. In some plants, many flowers grow close together to form a
composite structure that looks like a single flower. Other flowers might attract a wide variety of
pollinators.

The Angiosperm Life Cycle

Angiosperms undergo alternation of generations.

Male Gametophytes Meiosis produces four haploid spore cells. Each divides to produce a
generative and a tube cell. The male gametophyte with its two cells is then surrounded by a thick
wall that protects it. The entire gametophyte is a pollen grain.

Female Gametophytes A diploid cell undergoes meiosis to produce four haploid cells. One cell
undergoes mitosis, producing eight nuclei. Next, cells walls form seven cells, six with one
nucleus and a seventh with two. These seven cells are the female gametophyte, known as the
embryo sac.

Pollination The transfer of pollen to the female portions of the flower is called pollination.

Fertilization When a pollen grain lands on the stigma,

it grows a pollen tube. The “generative” cell divides and
forms two sperm cells. The pollen tube grows into the style, eventually reaching the ovary and
entering an ovule, resulting in double fertilization, where a diploid zygote and endosperm are
produced. This is distinct in angiosperms.

Vegetative Reproduction

Many flowering plants can also reproduce asexually by a process known as vegetative
reproduction. This process takes place naturally in many plants, and it can be used to produce
many copies of an individual plant. It does not require gametes, flowers, or fertilization.

Grade 9/Term 3/Biology 2

Because vegetative reproduction does not involve seed formation, a single plant can reproduce
quickly. In addition, asexual reproduction allows a single plant to produce genetically identical
offspring.

Fruits and Seeds

The development of the seed, which protects and nourishes the plant embryo, contributed greatly
to the success of plants on land. But the angiosperm seed, protected by a fruit, was an even better
adaptation.

Fruit and Seed Development Once fertilization of an angiosperm is complete, nutrients flow
from the vascular system into the flower to support the growing embryo within the seed. As
angiosperm seeds mature, ovary walls thicken to form a fruit that encloses the developing seeds.
The ovary wall surrounding a fruit may be fleshy, as it is in grapes and tomatoes, or tough and
dry, like the shell that surrounds peanuts. The peanuts themselves are seeds.

Seed Dispersal The seeds of many plants, especially those encased in sweet, fleshy fruits, are
often eaten by animals. The seeds are covered with tough coatings, allowing them to pass
through an animal’s digestive system unharmed. The seeds then sprout in the feces eliminated
from the animal and help the plant disperse its seeds. Wind and water also help to disperse seeds.

Seed Germination All seeds contain plant embryos in a state of dormancy, during which the
embryo is alive but not growing. Germination takes place when growth of the embryo resumes
and the seed sprouts into a plant. Dormancy can allow for long-distance seed dispersal, making it
possible for seeds to germinate under more ideal conditions.

I. Match the floral part with its description.

Floral Part Description
1. anthers A. Stalk with a stigma at the top
2. carpels B. Structures that produce male gametophytes
3. filament C. Structure that contains one or more ovules
4. ovary D. Outermost circle of green floral parts
5. petals E. Long, thin structure that supports an anther
6. pollen F. Floral parts that produce female gametophytes
7. sepals G. Yellowish dust that contains male gametophytes
8. stamen H. Male structure with an anther and a filament
9. stigma I. Brightly colored parts just inside the sepals
10. style J. Sticky, top portion of style

Grade 9/Term 3/Biology 3

II. Write True if the statement is true. If the statement is false, change the underlined word
or words to make the statement true.
______________ 11. In pollination, pollen grains are transferred to the ovary of a flower.
______________ 12. A pollen tube delivers one sperm to an ovule.
______________ 13. The fertilized egg in an ovule becomes the zygote of a new sporophyte.
______________ 14. Triploid tissue, called endosperm, forms in double fertilization.
______________ 15. In most monocots, the cotyledon remains underground.
______________ 16. In monocots, a cotyledon protects the young shoot as it emerges.
______________ 17. The hook of the new shoot of a germinating dicot protects the new
leaves from injury by the soil.
______________ 18. The primary root is the first root of a new plant.
______________ 19. Dormancy enables seeds to live under ideal growing conditions.
______________ 20. For many seeds, a long period of cold is required before dormancy
can end.

III. Complete the illustration by labeling the parts of the flower indicated.

Grade 9/Term 3/Biology 4

IV. Complete the following tables.

Table 1:

Term Definition

_______________________ Period when the plant embryo is alive but not growing

_______________________ Growth stage of a plant embryo

Table 2:

Term Definition

_____________________ A flowering plant with two seed leaves

_____________________ A structure containing one or more mature ovaries; its thick tissue
surrounds the seeds and helps carry them away from the parent plant

_____________________ A flowering plant with one seed leaf

_____________________ A flower structure that surrounds and protects seeds

Grade 9/Term 3/Biology 5

Table 3:

Leaves Vascular bundles Seeds Examples

Monocot Single cotyledon

Dicot Branched veins

V. Answer the following questions.

21. What is vegetative reproduction in plants?

22. Give an advantage and a disadvantage of vegetative reproduction to plants.

Grade 9/Term 3/Biology 6