Chapter 9 seed plants

Quick Review What are the 5 things we already know about the entire plant kingdom? What are the four main groups of plants? What are three examples of nonvascular plants? What are three examples of seedless vascular plants? Why is water important for both mosses and ferns? What two things does vascular tissue do for vascular plants?

9-1 Characteristics of Seed Plants What is a seed plant? Most plants on earth are seed plants. Seed plants out number seedless plants 10-1 on earth. Examples of seed plants: dandelions, rice, tomatoes, peas, cotton, oak, pine ALL SEED PLANTS SHARE TWO CHARACTERISTICS: Vascular Tissue Seeds to Reproduce AND MOST SEED PLANTS SHARE MORE CHARACTERISTICS: They have leaves, stems, and true roots They have complex life cycles with a sporophyte stage and a gametophyte stage.

In seed plants: Sporophyte is the plant you see. Gametophytes are microscopic. Vascular Tissue: Seed plants need vascular tissue to live on land so they can: Stand upright Work against gravity to deliver water and nutrients to the rest of the plant. There are two types of Vascular Tissue: Phloem- movement of food (from leaves DOWN to stems and roots) 2) Xylem- movement of water and nutrients (from roots to UP to stems and leaves)

Unlike seedless plants, seed plants do not need water to reproduce. Together they are called: Vascular Tissue Phloem Xylem Seeds Seeds are structures that contain a young plant inside a protective covering. Unlike seedless plants, seed plants do not need water to reproduce.

Seed plants do not need water to reproduce because sperm cells are delivered directly to regions near egg cells. All seeds have a similar 4 part structure: An Embryo Cotyledon Seed Coat Stored Food Embryo- The young plant that develops from the fertilized egg. IT already has the beginnings of roots, stems, and leaves. Cotyledon- Will develop into first leaf. Seed Coat- protects food supply and prevents drying out for long periods of time. Stored Food- Supplies growing plant with food.

Label the Seed Part Below: Cotyledon Embryo F Stored Food Seed Coat Structure Function

Seed Dispersal- the scattering of seeds To develop into a new plant, a seed needs: Light Water Nutrients After formed, seeds can be scattered far from where they were formed. When they land in suitable conditions, they can sprout and begin to grow into new plants. How are seeds dispersed? Animals- in fur or through digestive system Wind After a seed is dispersed, it can remain inactive for long periods of time, or grow right away.

Germination- The early stage of growth of the embryo. Steps of Germination: Seed absorbs water Stored food is used for growth Roots grow downward Leaves and Stems grow upward Seeds that are dispersed far from their parent have a better chance for survival. Why? Because they do not have to compete with their parent for food, water, light, and nutrients to grow.

Plant leaves vary greatly in size and shape. (pine needles, oak leaves, elephant leaves) *Important function of leaves: Leaves capture the sun’s energy carry out photosynthesis. Structure of a Leaf: Cuticle Surface Cells Upper Layer Cells Vascular Tissue Lower Layer Cells (*Xylem is inside of phloem) Stomata

Leaf Structures and Functions pg. 279 Cuticle Surface Cells Upper Leaf Cells Lower Leaf Cells Xylem Phloem Stomata

Photosynthesis Review The cells that contain the most chloroplasts with chlorophyll to absorb sunlight are in the upper layers of cells in leaves. Carbon Dioxide enters through the stomata. Water is absorbed in the plants roots and travel up through xylem. During photosynthesis sugar and oxygen are produced. The sugar enters the phloem and travels throughout the plant. The oxygen exits through stomata. Therefore the formula for photosynthesis is: __________________________________

Controlling Water Loss Q: Why is it so easy for water to evaporate from a plant? A: Because such a large amount of surface area of a leaf is exposed to the air. The process of evaporation in plant leaves is called transpiration. Q: How can plants control the loss of water through transpiration? A: By closing their stomata (for example when the temperature is hot.)

The stem of a plant has two important functions: Stems The stem of a plant has two important functions: Carry substances between the roots to the leaves. Provide support for the leaves to be held up to the sunlight. *some stems also store food- example: asparagus Stem Structure- Stems can either be: Woody Herbaceous -Hard, Rigid -Outer covering of bark -Inner “heartwood” for support -Soft - Flower stems, weed stems are examples.

Typical Layers of a Woody Stem Pith Heartwood Xylem Sapwood Cambium Phloem Bark Outer Bark

Rainy years- thick rings, more xylem are produced Structure Function Outer Bark Phloem Cambium Sapwood Heartwood Pith Annual Rings Made of xylem Each ring (pairing of one dark with one light) represents one year of the growth of the tree. The width of each ring can provide clues to past weather conditions- such as rainfall: Rainy years- thick rings, more xylem are produced Dry years- narrow rings, less xylem Can help scientists infer what years had droughts.

Roots Roots anchor the plant in the ground and absorb water and nutrients from the soil. The more roots there are, the more surface area there is to absorb more water and nutrients. Types of Roots Taproot- one long, thick, main root Example- carrot, cacti, dandelions 2) Fibrous- Several main roots that branch repeatedly to form a tangled mass Example- lawn grass, corn, most trees

Root Structure Q: Why is the root cap covered with dead cells? Phloem Xylem Cambium Surface Cells Area of Dividing Cells Root Hair Q: Why is the root cap covered with dead cells? A: To protect the root from injury and rocks in the soil. Q: Why are root hairs important? A: They increase surface area to absorb nutrients.

Person A Person B The food Supply for a plant 1) Moves water upward in a plant Cotyledon Xylem 2) Move food downward in a plant 2) Early growth stage of a seed Phloem Germination 3) Holds young plant 3) Openings on underside of a leaf Seed Stomata 4) Protects roots from rocks 4) Evaporation in a plant Root Cap Transpiration 5) Produces new xylem and phloem 5) Beginnings of roots, leaves, stems Cambium Embryo

9-2 Gymnosperms What is a gymnosperm? A seed plant that produces “naked” seeds because they do not have a protective covering. Every gymnosperm: 1) has naked seeds 2) has needlelike or scalelike leaves 3) has deep-growing root systems Types of Gymnosperms: Cycads Ginkgo Gnetophytes Conifers

1) cycads- Palm-like plants with large cones; found in tropical climates. 2) ginkgoes- similarities to fossils indicate it is one of the oldest seed plants, grow as tall as 25 meters, tolerate pollution well. 3) gnetophytes- reproductive scales clustered into cones; very small phylum found in deserts. 4) Conifers- most common gymnosperms; includes pines, spruce, firs, and cedars, keep needles year round.

Sporophyte Pine Tree produces male and female cones. 2a) Each female has two ovules. 2b) Male cones have pollen grains with sperm cells. 3) Egg cell forms inside of each ovule 4) Wind scatters pollen grains and they get stuck in ovules. 5) Sperm and egg cells join. 6) Fertilized egg becomes and embryo- seed with protective coat. 7) Wind disperses seed to land and grow into young sporophyte. 1 2a 2b 3 7 6 4 5

Pollination and Fertilization Pollination- the transfer of pollen from the male reproductive structure to the female reproductive structure. The wind plays in important role in gymnosperms. The wind carries the pollen grain to the ovule. The ovule produces a sticky substance to trap the pollen. The ovule seals the pollen grain in. Fertilization takes place inside the scale.

Seed Dispersal As the seeds develop, the female cone increases in size. The cones position may change on the branch as well. Cones with mature seeds- point down Cones with immature seeds- point up When the seeds are mature, the scales open. The wind shakes the seeds out and carries them away. Only a few new seeds will land in a suitable environment to grow.

9-3 Angiosperms What are angiosperms? Have flowers Have fruit Flower- reproductive structure of an angiosperm Fruit- the ripened ovary- part that grows from the flower that protects the seeds that are enclosed in it. Most numerous type of plant on earth Grow all over the world in all climates and even in oceans.

The Structure of Flowers All flowers have the same function: reproduction. Parts: Petals- the colorful structures that you see when flowers open that attract certain insects and animals for pollination. Sepals- leaflike structure that covers the flower when it is still a bud that protect the developing flower. Stamens- male reproductive parts of a flower. - Filament- stalk part of stamen - anther- knob part where pollen is produced

The Structure of Flowers (cont.) 4) Pistil- female reproductive organ of a flower - stigma- sticky tip that attracts pollen - style- slender tube for pollen to travel - ovary- contains ovules where fertilization takes place. Stigma Anther Stamen Filament Pistil Style Petal Ovary Ovule Sepal

Reproduction 1st- The pollen falls on a stigma 2nd- In time, the sperm cell and the egg cell join together in the ovule. 3rd- The zygote develops into the embryo part of the seed. Pollination and Fertilization A flower is pollinated when a pollen grain falls on a stigma. Most angiosperms are pollinated using insects, bats, or birds. After the pollen reaches the ovule, fertilization takes place and the zygote develops into the seed embryo.

1- Angiosperm produces flowers 2a-egg cell is produced in ovules 2b- anther produces pollen grains 3- pollen gets trapped on the stigma 4- sperm travels and joins the egg 5- The ovule develops into a seed 6- the ovary itself develops into a fruit 7- the seed grows into a new plant 1 2a 2b 7 3 6 5 4

The seed is in the inside of the fruit. Seed Dispersal The seed is in the inside of the fruit. Animals will eat the fruit and leave the seeds to germinate and grow somewhere new. Obviously apples, cherries, and grapes are fruits with seeds (and therefore are angiosperms)…. But so are things you normally would call vegetables: tomatoes, squash Label the embryo and the ovary in each fruit:

Monocots: examples: lily, corn, palms Single cotyledon Parallel veins Floral parts in multiples of 3. Vascular bundles scattered Fibrous roots

Dicots: Examples: roses, tomatoes, oaks Two cotyledons Branched veins Floral patterns in multiples of 4 or 5 Vascular bundles in a ring Taproot

Angiopserms and the Living World Angiosperms are an important source of food, clothing, and medicine for other organisms. Food Humans: eat vegetables, fruits, and grains that are all angiosperms. Herbivores: eat grasses and other plants that help form food chains in ecosystems. Clothing and other products Humans get clothing from cotton which is an angiosperm. Furniture is made from wood from trees that are angiosperms. Medicine Aspirin was first made from a substance found in willow tree leaves.

9-4 Plant Responses and Growth Tropisms A plant’s growth response toward or away from a stimulus is called a tropism. Touch, light, and gravity are three important stimuli to which plants respond. Touch- response called thigmotropism- as a vine grows, it coils around anything it touches. Light- response called phototropism- plants bend toward the sun as it changes levels in the sky. Gravity- response called gravitropism- positive is working with gravity (roots), negative is working against gravity (stems).

Plant Hormones Hormone- chemical that affects how the plant grows and develops. In addition to tropisms, plant hormones also control germination, the formation of flowers, stems, and leaves, the shedding of leaves, and the development and ripening of fruit. Auxin- an important plant hormone that speeds up the rate at which plant cells grow, that allows the stem to bend toward the light.

Life Spans of Angiosperms Annual- Life span is one year long, need to be replanted every year. Biennial- Life Cycle is two years long, need to be replanted every two years. Perennial- Life cycle lasts longer than two years, come back every new growing season.