Section 6.2 : Kingdom Plantae pgs. 169-181

Section 6.2:Kingdom Plantae

pgs. 169-181

Four Groups of Plants

1. Mosses & relatives2. Ferns & relatives3. Cone-bearing plants4. Flowering plants

1. Mosses & Relatives(Non-Vascular Plants)

Three divisions of non-vascular plants:1. Mosses (Bryophytes)2. Hornworts (Anthocerophytes)3. Liverworts (Hepatophytes)

1. Mosses & Relatives(Non-Vascular Plants)

• Have no roots• Instead have small root-like

structures called rhizoids.• Grow in mats of low, tangled

vegetation that can hold water like a sponge.

Mosses (Bryophytes)

• Common in moist, shaded areas.• Sphagnum moss is valuable as it is highly

water absorbent and nutrient rich (peat moss).

2. Ferns & Relatives(Seedless Vascular Plants)

• Have vascular tissue.• Grow taller and live in a wider range of

habitats compared to mosses.• Ex. Whisk Fern, Club Mosses, Horsetails

Seed-Producing Vascular Plants

Made up of 2 groups that disperse using seeds:

Cone-Bearing Plants (Gymnosperms)Flowering Plants (Angiosperms)

Seeds enable plants to reproduce sexually without water.

3. Cone-Bearing Plants(Gymnosperms)

• They have roots, stems & leaves.

• They have seeds exposed on the surface of cones. Ex. Conifers (cone-bearing)

• Female cones develop ovules in archegonia that grow on the upper surface of each cone scale.

• Male cones produce microspores that develop into pollen grains (dispersed by wind)

• When pollen lands next to the archegonia, it produces a pollen tube.

• Sperm passes along it to get to the egg.

4. Flowering Plants(Angiosperms)

• Grow and develop seeds that are enclosed within a fruit.

• Include trees, shrubs, grasses, etc…

4. Flowering Plants(Angiosperms)

• Divided into two large classes based on the number of seed leaves on the embryo within the seed:1. Monocots: one seed leaf

(grasses, lilies, orchids, irises)2. Dicots: two seed leaves (roses,

peas, cacti, daisies, maple trees)

Seed Leave in the Embryo(Cotyledons)

Angiosperm Reproduction

• Female reproductive organ is the pistil.

• During pollination, the pollen grain grows an extension called a pollen tube, to carry sperm cells to the ovule.

• The sperm & egg unite to form a zygote which divides to produce an embryo with an immature root, stem & one or two seed leaves.

• The wall of the ovule hardens and becomes a protective seed coat.

** Know figure 6.13 on page 176.

Flower Anatomy

Can you identify these parts?

Pollination Adaptations

• Most methods of pollination involve insects, birds, bats, etc.

• Color, shape & scent of the flower helps the pollinator recognize the source of food.

Pollination

• Angiosperms can live nearly on every region on Earth, but could not do so without the presence of animals to help in pollination.

Self-Pollination• Single plants often produce many flowers

which can create conditions for self-pollination.

• Self-pollination produces genetically identical offspring.

Seed Structure

• The hard case of the seed allows the embryo inside to survive adverse conditions such as dry & hot conditions.

• Angiosperm seeds are further protected by the fleshy walls of the ovary.

Videos

How Stuff Works – Pollination Video (1:48)

Angiosperms: The flowering plants (20 min)

Section 6.2:Review Questions

• Do the handout called “Plant Reproduction”.• Do the handout called “Table 2: Plants

Worksheet”.• Do question #’s 1-9 on page 181.

Section 6.2Answers

1.a) Name the four broad groups into which the plant kingdom is divided.

1. Non-vascular (mosses)2. Vascular non-seed bearing (ferns)3. Vascular cone-bearing (gymnosperm)4. Vascular flowering (angiosperm)

1. b) What key feature or features are the basis for this grouping?

The key features are the presence or absence of a vascular system & mode of reproduction.

2. What are the products of meiosis in the four different groups of plants?

In ferns and mosses, meiosis produces spores. In angiosperms and gymnosperms, meiosis produces eggs & pollen.

3. How do bryophytes compare with plants in the other three major groups?

Bryophytes are the mosses and their relatives – simple non-vascular plants. They lack vascular tissue and have no true roots, stems or leaves.

4. Ferns are more diverse and widespread than any other division of non-vascular and spore-producing plants. What features of ferns account for this?

Having a vascular system and a dominant sporophyte generation enable ferns to be more diverse and widespread.

5. For each pair of terms below, explain what they have in common and how they differ.a) carpel and stamenBoth are reproductive organs of flowering plants; the carpel is the female organ, and the stamen is the male organ.

5. b) flower and coneBoth are seed-bearing structures.

Flowers grow on flowering plants, and cones grow on coniferous plants.

5. c) Angiosperm & gymnosperm

Both are large-seed bearing, vascular divisions of the plant Kingdom. Angiosperms are flowering plants with seeds encased in fruits. Gymnosperms are cone-bearing plants with exposed seeds.

d) Seed & spore

Both are reproductive structures. Seeds are matureovules that contain a sporophyte embryo

surroundedby a protective coat. Spores are haploid

reproductivecells that do not require fertilization.

6. What is the function of pollination? Explain why pollination alone does not ensure successful reproduction.

Pollination is the process by which pollen grains from the anther reach the stigma of the pistil. On its own, pollination does not ensure successful reproduction because the pollen grain must grow a pollen tube to reach the ovule.

7. a) Can a gamete develop into a complete plant by itself, without fertilization? Explain.

Because a gamete is either a sperm or egg cell, it cannot develop into a complete plant by itself without being fertilized.

7. b) Can a spore develop into a complete plant by itself, without fertilization? Explain.

A spore can develop into a complete plant by itself because it does not require fertilization.

8. Explain why seeds can be referred to as “plants in storage” while spores cannot.

Seeds contain all that is necessary for producing a typical plant; the leaf, stem and root are all found within the seed embryo. Spores merely develop into sperm- and egg-producing gametophytes that form new plants.

9. a) Explain the reproductive advantage of preventing self-pollination.

Preventing self-pollination ensures variation through sexual reproduction. The genetic information of another individual is incorporated into the zygote.

9. b) Explain the reproductive advantage of permitting self-pollination.

Permitting self-pollination allows the plant to complete the reproductive cycle and produce offspring on its own. However, due to genetic similarity, the offspring may be less likely to survive changing environmental conditions.