"Main Groups of Plants" PPT download

Description

"Main Groups of Plants" PPT download

Part One: Situation Import

How do plants in nature generally reproduce?

learning target

1. Understand the morphological and structural characteristics of seed plants and understand that seed plants are the highest group of plants.

2. Understand the relationship between seed plants and humans, and cultivate students’ scientific attitude of loving nature and seeking truth from facts.

PPT of the main groups of plants, part 2: seed plants

Seed plants are the highest group of plants. All seed plants share two basic characteristics:

(1) There are vascular tissues in the body - phloem and xylem;

(2) Can produce seeds and use seeds to reproduce offspring.

Observe the cones of pine trees (commonly known as "pine cones") and apple fruits, and pay attention to whether they have seeds and the status of the seeds. Think about it, what is the difference in the implantation status of their seeds?

The cones of pine trees and the fruits of apple trees contain seeds, so pine trees and apple trees are both seed plants. However, they are obviously different: the seeds of pine trees are naked and not covered with pericarp, so they belong to gymnosperms. The seeds of the apple tree are not exposed and are covered with peel, so they are angiosperms. That is to say, seed plants can be divided into two categories: gymnosperms and angiosperms. Among gymnosperms, pine is a common type.

PPT of the main groups of plants, part 3: gymnosperms

Gymnosperms are the lower class of seed plants. There is no ovary wall covering the outside of their ovules, they do not form fruits, and their seeds are exposed, so they are called gymnosperms.

Pine trees are monoecious plants. In spring, male cones growing at the base of new branches produce large amounts of pollen. Each pollen grain has two air sacs, so the pollen can easily be blown away by the wind. The female cone (pictured on the right) attached to the top of the new branch has exposed ovules with egg cells inside. Pollen germinates within the ovule to form a pollen tube, which contains sperm. The sperm fuses with the egg cell, completing fertilization. It can be seen that the fertilization process of pine trees has escaped the restrictions of water.

1. Main characteristics of gymnosperms

(1) Able to produce seeds. The ovule is naked, not surrounded by the ovary wall, therefore, the seed is naked, not surrounded by the pericarp.

(2) The roots, leaves, and stems are well developed and the fertilization process does not require water, so they are suitable for living in dry places.

2. Common gymnosperms

Cedar, Pinaceae, Cedar genus. Evergreen trees. Often planted in the center of lawns and squares, it is a world-famous ornamental tree. Cedar is a positive tree species, with certain tolerance to shade and cold, and strong drought tolerance. It likes deep soil and well-drained soil, and is afraid of water accumulation. Cedar is a shallow-rooted tree species that grows quickly and is a fast-growing tree species.

Pinus tabulaeformis, Pinaceae, genus Pinus, is an evergreen tree, also known as Northeastern black pine and short masson pine. The trunk is tall and vigorous, evergreen all year round, and is not afraid of wind, snow and cold. The trunk is spread out, tower-shaped in the prime of life, and disc-shaped or umbrella-shaped in old age. Shape, old branches spread diagonally, green, can be planted alone, in clusters, or in pure forest groups in garden planting.

3. The relationship between gymnosperms and humans

There are about 800 kinds of gymnosperms in the world, and my country has more than 250 kinds, ranking first in the world. Therefore, my country is known as the "hometown of gymnosperms".

PPT of the main groups of plants, part 4: angiosperms

Angiosperms occupy most of the modern earth's land space and are the main component of the world's vegetation. Flowers are the unique characteristics of angiosperms, so they are also called flowering plants. The appearance of perianth can improve pollination efficiency and achieve cross-pollination. The seeds are enclosed in a tight pericarp so that the ovules are better protected. The fruits of angiosperms have different colors, aromas, tastes and various cracking methods, and often have various hooks, spines, wings or hairs, etc. These characteristics also play an important role in protecting the seeds from maturation, helping the seeds to disperse and reproduce. .

Angiosperms have a double fertilization phenomenon. When two sperm cells enter the embryo sac, one sperm cell combines with the egg cell to form a fertilized egg, which will develop into an embryo in the future. The other one combines with the two polar nuclei to form the endosperm.

1. Main characteristics of angiosperms

(1) Having roots, stems, leaves, flowers, fruits, and seeds.

(2) The ovule is covered by the ovary wall, so the seed is covered by the fruit.

(3) The fertilization process does not require water and the fertilization method is double fertilization.

2. Classification of angiosperms

Among all angiosperms, they can be divided into two major categories, namely dicots and monocots.

The root system of dicotyledonous plants is basically a taproot system with a well-developed taproot; many are woody plants, and the stems can be continuously thickened; the leaf veins are reticular veins; the number of sepals and petals in the flowers is 5 or 4. If the petals are united, there are 5 or 4 lobes.

3. Common angiosperms

Poplar tomentosa is a high-quality native tree species unique to my country and is distributed over a wide area. Poplar tomentosa is deeply loved by the people for its excellent material, strong adaptability and stress resistance. It is the main afforestation tree species in the vast northern areas of my country.

PPT on the main groups of plants, part 5: training to meet standards

1. Some students put rice, watermelon, and pine trees into one category, and kelp, liverworts, and ferns into another category. It is classified based on ( )

A. With or without roots B. With or without seeds

C. Aquatic or terrestrial D. With or without fruits

2. Compared with pine trees and peach trees, the main difference is ( )

A. Pine tree seeds are covered with pericarp.

B. Pine tree seeds are exposed and not covered with pericarp.

C. The cones of pine trees are covered with fruits

D. Pine female cones are composed of ovules and ovary walls

3. Among the following plants, which ones are gymnosperms ( )

A. Metasequoia B. Selaginella C. Hornwort D. Liverwort

4. The most widely distributed and diverse plant group on the earth is ( )

A.Algae B.Bryophytes C.Gymnosperms D.Angiosperms

5. The main characteristics that distinguish angiosperms from gymnosperms are ( )

A. There are roots, stems, leaves, flowers, fruits and seeds B. There are seeds

C. There is a pericarp covering the outside of the seed. D. There is no pericarp covering outside the seed.

Keywords: Free download of Biology PPT courseware for the second volume of the eighth grade edition of Beijing Normal University, PPT download of the main groups of plants, .PPT format;

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Update Time: 2024-07-06

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