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Plants and Animals
Plant Parts – The Roots
Common Parts
 Almost all plants have three main parts:
 Roots
 Stems
 Leaves
Roots
 Most roots act as anchors.
 They also take in water from the soil through tiny parts
called root hairs.
 Roots can store excess food for plants.
Roots can adapt to their environment.
 Desert roots spread far out but
stay close to the surface so they
can collect as much rain as
possible.
 Forest roots do not need to
spread out; they go deep into
the ground to anchor the trees.
Some trees have prop roots
that begin above ground to keep
them very secured.
Roots can adapt to their environment.
 Many plants have fibrous roots which look like little tree
branches; helps prevent soil erosion and water loss.
 Some plants have tap roots that grow straight down into the
ground, so they are able to reach water deep in the ground.
Roots can adapt to their environment.
 In tropical areas, roots attach themselves to the trees and take
water in directly from the air.
Roots can adapt to their environment.
 Storage roots store extra nutrients, like sugar, inside of them.
 We eat many of these vegetables.
Plants and Animals
Plant Parts – The Stem
Stems
 Hold plants up
 Support the leaves in the sunlight
 Carry water and nutrients from roots to leaves
Stems
 Most grow upwards, turning during the daylight.
 Some grow sideways.
 Every time the stem touches the ground, it anchors and starts
a new plant.
Different types of stems
 Desert stems store food and water for the plant to survive.
 Small plants usually have soft, green stems. These stems
usually die at the end of the growing season.
 Large plants, like trees, usually have tough, wood stems.
These stems can live for hundreds of years.
Inside the Stem
 Most plants contain narrow tubes that carry water,
minerals, and foot to different parts of the plant.
 Xylem: carries water and minerals up from the root to the
leaves.
 Phloem: carries nutrients down from the leaves to the
roots.
Inside the Stem
 In soft stems, xylem and phloem are arranged in bundles
throughout the stem.
 In tough stems, xylem and phloem are arranged in separate
rings.
Plants and Animals
Plant Parts – Leaves &
Photosynthesis
Leaves
 Come in many shapes, sizes,
and arrangements.
 Most are very thin and flat
to trap sunlight.
 All leaves contain
chloroplasts, which have
a chemical called
chlorophyll in them –
used in the process of
photosynthesis.
Photosynthesis
 The process in which plants make food from the sunlight.
 Photo = light; synthesis = putting together
 Plants use water, carbon dioxide, and sunlight to make food
(sugar/glucose) and oxygen.
 Plants use some of the glucose that is made as food, and
stores the rest as starch.
Photosynthesis
Cellular Respiration
 When plants have to use this stored starch for energy, they
go through the process of cellular respiration.
 Plants take glucose and oxygen to make carbon dioxide,
water, and food energy.
 Humans also do this.
Leaf structure
 Leaves have veins going through them, which hold the
xylem and phloem.
 When the veins are full of water/nutrients, the plant does
not wilt.
Leaf structure
 The upper surface of the leaf: upper epidermis.
 Thin and flat; traps sunlight.
 Has a waxy covering which helps prevent water loss; called
a cuticle.
Leaf structure
 The bottom layer is the lower epidermis.
 This layer contain several tiny pores, called stomata, that
can open and close to allow water and gases to move in and
out of the leaf.
 Guard cells are located around the stomata, and change
their shape forcing the stomata to open or close.
Leaf structure
Plants and Animals
Non-vascular vs.
Vascular plants
Non-vascular plants
 Plants that do not contain xylem and phloem are called
non-vascular.
 These plants do not use tubes to move water and nutrients;
instead, it just passes from one cell to another.
 They are limited in size because they do not have structure.
 Example: moss and liverworts
Non-vascular plants
 Do not have flowers, so they do not use seeds to reproduce.
 They use spores – single reproductive cells that grow into
new plants.
Simple Vascular plants
 Like moss, these plants use spores to reproduce.
 They also have two different stages in their life cycle.
 Examples include ferns and horsetails.
Seeded Plants
 Spores are not as successful as growing into new plants, so
the majority of plants fall into two groups: gymnosperms
and angiosperms.
 Both of these types of plants use seeds to reproduce and
form new plants.
Gymnosperms
 Plants that have unprotected
seeds.
 Most common: conifers,
or cone-bearing plants.
 Pine trees, evergreens,
firs, etc.
Conifers
 Most conifers produce both male
and female cones on the same tree.
 Male cones produce pollen.
 Female cones can be as small as 2
cm or as large as almost 2 feet!
 They have woody plates, called
scales, that protect them.
 Plants
Plants and Animals
Angiosperms
Angiosperms
 Flowering plants
 Grasses, herbs, shrubs, trees, etc.
Angiosperms
 Pollinated by wind, insects, and other small animals.
 Bright colors, shapes, and odors of flowering plants attract
pollinators to them, and then the insects and animals
carry the pollen on them.
Angiosperms
 Angiosperms produce fruit that protects their seeds,
including apples, oranges, tomatoes, peanuts, and acorns.
 Keeps animals away from seeds and protects it in cold
weather.
Plants and Animals
Plant Reproduction –
Gymnosperms & Angiosperms
Gymnosperms
 Remember: the same tree can contain both male and
female cones that produce male and female cells.
 When these seeds join, they are able to produce new
plants.
Angiosperms
 In angiosperms, male and female reproductive parts can be
found on the same flower.
 The male parts make up the stamen and produce pollen.
 The female parts make up the pistil and produce eggs.
 We already learned that pollen can be carried by wind or
pollinators to places where the eggs may be.
Angiosperms
 Before a flower blooms, it is called a bud.
 During this time, everything inside of the flower is covered
by the sepals.
 Once bloomed, the sepals look like green petals.
Angiosperms
 Inside of the petals are the stamens, which are long, thin
stalks.
 A flower can have several stamens, and each stamen has an
anther at the top of it that produces pollen.
Angiosperms
 At the center of the flower is one pistil.
 Most of it is a long, narrow tube called the style. At the
top of the style is the stigma, which is sticky to hold on to
the pollen. (pollination)
 At the bottom of the style is the ovary, which holds the
eggs.
Angiosperms
Methods of Pollination
 Self-pollination: the pollen of one flower joins a stigma
on the same flower, normally due to wind.
 Cross-pollination: the pollen of one flower joins a
stigma on a different flower; more common.
 Cross-pollination allows for more genetic diversity among
plants; Gregor Mendel used this process with his pea
plants.
Plants and Animals
Seeds
Seeds
 Seed coat: outer covering that protects the seed.
 Embryo: inside of the seed; a tiny plant that has potential
to grow.
Seeds
 Cotyledons: storage for food and water kept inside of the
seed to supply nutrients to the seed.
 Monocot: plants with one cotyledon in their seeds (corn)
 Dicot: plants with two cotyledons in their seeds (beans)
Seed Dispersal
 Plants are adapted to disperse (scatter) their seeds.
 Maple trees have wing-shaped fruits that spin to slow down
their fall, allowing the wind to carry them.
Seed Dispersal
 Many plants depend on animals, like oak trees. Squirrels
carry their acorns to new places and bury them.
Seed Dispersal
 Some seeds have a rough covering called a bur. These stick
to the fur of passing animals and eventually fall off.
Seed Germination
 Seeds need soil, warm temperatures, and enough water to
grow.
 When the conditions are right, a seed will sprout, or
germinate, and begin the next stage of its life.
Seed Germination
 Step 1: take in water.
 Step 2: the seed coat splits due to swelling.
 Step 3: the root begins to develop.
 Step 4: stem emerges and grows toward light.
 Step 5: growing plant, called seedling, uses food storage
to grow.
 Step 6: leaves grow and use photosynthesis to make food.
 Step 7: once the plant is growing strong enough, the
cotyledons drop off.
Seed Germination