Download Plants

Plants
Characteristics of All Organisms
All living organisms share the following characteristics:
1. They obtain and use resources for energy.
a. All organisms must obtain resources, such as food, oxygen, and water,
which provide required energy to perform the basic processes of life, such
as growing and developing, or repairing injured parts.
b. Autotrophs: (for example plants) provide their own food energy through
the process of photosynthesis
c. Heterotrophs: (for example animals) must find an external source for food
d. Energy is released from food in most organisms through the process of
respiration.
2. They respond to stimuli.
a. Stimulus: any change in an organisms surroundings that will cause the
organism to react.
i. Examples of environmental stimuli: changes in the amount of light
present; changes in temperature; sound, amount of water; space;
amounts or types of food; or other organisms present
ii. Examples of internal stimuli: hunger, tired, or thirst
b. Response: the reaction to the stimulus; can be an action or behavior
performed by the organism
3. They reproduce.
a. Organisms have the ability to reproduce, or produce offspring that have
similar characteristics as the parents.
b. Two Types of Reproduction:
i. Asexual Reproduction: a reproductive process that involves only
one parent and produces offspring that is identical to the parent
ii. Sexual Reproduction: a reproductive process that involves two
parents; the egg (female reproductive cell) and sperm (male
reproductive cell) from these two parents combine to make an
offspring that is different from both parents
4. They grow and develop.
a. Growth: the process whereby the organism becomes larger
b. Development: the process that occurs in the life of the organism that
results in the organism becoming more COMPLEX structurally
c. Organisms need energy to grow and develop.
Taxonomy of Organisms
1. Taxonomy: the study of how scientists classify organisms
2. The modern classification system uses a series of levels to group organisms.
3. An organism is placed into a broad group and is then placed into more specific
groups based on its structures.
4. The levels of classification (from broadest to most specific) include:
a. Kingdom
i. Most scientists currently support 5 kingdoms (Plants, Animals, Fungi,
Protists, Monerans)
ii. Organisms are placed into kingdoms based on their ability to make
food and the number of cells in their body
b. Phylum (plural phyla)
i. In the Plant kingdom, phyla are sometimes referred to as divisions.
ii. Plants are divided into two groups: vascular and nonvascular
iii. In the Animal kingdom, there are 35 different phyla. These phyla
can be divided into two groups: vertebrates and invertebrates
c. Class –becomes more specific and will include fewer organisms that have
more in common with each other
d. Order –becomes more specific and will include fewer organisms that
have more in common with each other
e. Family –becomes more specific and will include fewer organisms that
have more in common with each other
f. Genus (plural Genera)
i. Contains closely related organisms
ii. Used as the first word in an organism’s scientific name
g. Species
i. Consists of all the organisms of the same type which are able to
breed and produce young of the same kind
ii. Used as the second word in an organism’s scientific name
5. The more classification levels an organism shares with another, the more
characteristics they have in common.
6. The scientific name of an organism is made up of its genus and species.
a. It is written in italics (Genus species) with the genus capitalized.
b. For example, Canus lupus is the scientific name for the wolf and Pinus
taeda is the scientific name for the loblolly pine.
Characteristics of Various Groups of Plants
1. The organisms in the Plant Kingdom are classified into groups based on several
characteristics, for example:
a. How they absorb and circulate fluids (vascular and nonvascular)
b. How they reproduce (spores or seeds)
c. Method of seed production (cones or flowers)
d. Type of seed leaf (monocot or dicot)
2. Plants are commonly classified into two major groups based on their internal
structures.
a. Vascular Plants
i. Largest group in the Plant Kingdom
ii. Have a well-developed system for transporting water and food;
they have true roots, stems, and leaves.
iii. Contain tube-like structures that provide support and help circulate
water and food throughout the plant
iv. Xylem: transports water and minerals from the roots to the rest of
the plant
v. Phloem: transports food from the leaves to the rest of the plant
vi. Examples: trees, many shrubs with woody stems, dandelions, and
tomato plants with soft herbaceous stems
b. Nonvascular Plants
i. Do NOT have a well-developed system for transporting water and
food; therefore, do NOT have true roots, stems, or leaves
ii. Must obtain nutrients directly from the environment and distribute it
from cell to cell throughout the plant
iii. Usually results in these plants being very small in size
iv. Examples: mosses, liverworts, and hornworts
3. Classification based on Reproduction:
a. Seed Producing:
i. Plants that reproduce through seeds; make their own seeds
ii. Seeds contain:
1. Embryo: the beginning of the roots, stems, and leaves
2. Cotyledon(s): stored food
3. Seed coat: surrounds and protects the seed
iii. Two major groups are
1. Cone-bearing plants
2. Flowering plants
b. Spore-Producing:
i. Plants that produce spores for reproduction instead of seeds
ii. Spores are much smaller than seeds
iii. Almost all flowerless plants produce spores.
iv. Examples: mosses and ferns
4. Method of Seed Production:
a. Flowering plants
i. Grow seeds inside an ovary which is embedded in a flower
ii. The flower then becomes a fruit containing the seed
iii. Examples include: most trees, shrubs, vines, flowers, fruits,
vegetables, and legumes
b. Cone-bearing plants
i. Most cone-bearing plants are evergreen with needle-like leaves
ii. Conifers NEVER have flowers, but produce seeds in cones.
iii. Examples include: pine, spruce, juniper, redwood, and cedar trees
5. Monocot vs. Dicot:
a. Monocot
i. Monocotyledon (monocot): a seed with ONE food storage area
ii. Flower petals are in threes or multiples of threes
iii. Leaves are long and slender with veins that are parallel to each
other
iv. Vascular tube structures are scattered randomly throughout the
stem
v. Examples: grass, corn, rice, lilies, and tulips
b. Dicot
i. Dicotyledon (dicot): a seed with two food storage areas
ii. Flower petals are in four or five or multiples of four or fives
iii. Leaves are broad with branching veins
iv. Vascular tube structures are in circular bundles
v. Examples: roses, dandelions, maple, and oak trees
Basic Functions of Structures of Flowering Plants
1. Flowering plants have special structures that function for defense, survival, and
reproduction.
2. Structures for Defense
a. Plants have structures for defense that protect them from threats and
without these defenses the plant might die.
b. Examples:
i. Thorns that can defend the plant from being eaten by animals
ii. Fruits and leaves with poisons so that they are not being eaten
iii. Thigmotropism: the ability to close its leaves when touched
3. Structures for Survival
a. Plants have structures that allow them to survive in their habitats when the
conditions are not suitable.
b. Leaves function as the site of photosynthesis, respiration, and transpiration
in plants.
c. Stems support the plant and hold the leaves up to the light. Stems also
function as food storage sites.
i. Xylem: in the stems transport water from roots to the leaves and
other plant parts
ii. Phloem: in the stems transport food made in the leaves to growing
parts of the plant
d. Roots help anchor the plant in the ground.
i. Also absorb water and nutrients from the soil and store extra food
for the plants
ii. More surface area on the root that is available, the more water
and nutrients it can absorb
iii. Root hairs help to increase this surface area.
e. There are two types of roots: fibrous roots and taproots
i. Fibrous roots: consist of several main roots that branch off to form a
mass of roots (Examples: grass, corn, and some trees)
ii. Tap roots: consist of one large, main root with smaller roots
branching off (Examples: carrots, dandelions, or cacti)
f. Seeds have special structures that allow them to be dispersed by wind,
water, or animals.
g. The seed coat helps protect the embryo from injury and also from drying
out.
4. Structures for Reproduction
a. Flowers
i. Flowers produce seeds.
ii. Many flowers contain both male and female parts needed to
produce new flowers
iii. Flower petals are often colorful or have a scent to attract insects
and other animals, pollinators.
b. Stamen
i. The male part of the flower that has an anther on a stalk (filament)
ii. The anther produces the pollen that contains the sperm cells.
c. Pistil
i. The female part of the flower that contains:
1. Ovary: contains the ovules where the egg cells are
produced
2. Stigma: the sticky top where pollen grains land
3. Style: a stalk down which the pollen tube grows after
pollination has taken place
d. Seed
i. The ovule that contains the fertilized egg (embryo) from which new
plants are formed; ovule becomes the seed
ii. A fruit that is formed from the ovary often protects them
Life Cycle of Flowering Plants
**All flowering plants have similar life cycles. These life cycles include distinct stages.**
1. Germination
a. When seeds are dispersed from the parent plant, they can either lay
dormant or they can begin to grow immediately given right conditions.
b. Germination: the early stage of seed growth
c. The roots begin to grow down, while the stem and leaves grow up.
2. Plant development
a. Over time the seed grows into a mature plant with the structures
necessary to produce more plants.
3. Pollination/Fertilization
a. When pollen, which is produced in the stamen of a flower, transfers from
stamen to pistil (pollination) and then enters the ovule, which is located in
the ovary of a flower, fertilization occurs.
4. Seed production
a. Once the ovule is fertilized it develops into a seed.
b. A fruit (fleshy, pod, or shell) then develops to protect the seed.
c. Seeds are structures that contain the young plant surrounded by a
protective covering.
Processes of Sexual and Asexual Reproduction of Flowering Plants
1. Sexual reproduction
a. A process of reproduction that requires two parents; a sperm cell (in
pollen) and an egg cell (in the ovule) to combine to produce a new
organism
b. All flowering plants undergo sexual reproduction.
2. Asexual reproduction
a. A process of reproduction that involves only one parent plant or plant
part and produces offspring identical to the parent plant
b. Many plants can grow new plants asexually from their plant parts.
c. If a plant is cut or damaged, it can sprout new growth from the stems,
roots, or leaves.
d. Plants use a variety of parts to produce new plants such as:
i. Tubers and bulbs
1. These are all types of underground stems.
2. The “eyes” or buds of tubers, for example potatoes, grow
into roots and shoots to produce a new plant
3. Bulbs, for example onions, are big buds made of a stem and
special types of leaves
ii. Runners
1. These are all types of stems that run along the ground.
2. New strawberries or some ivy grow from the tips of runners.
3. Many lawn grasses grow from runners.
iii. Stem cuttings
1. When a piece of cut stem is planted, roots may form from
the cutting, and then a full plant develops.
2. Sugar cane and pineapple are examples of plants grown
from stem cuttings
iv. Roots
1. Some fruit trees and bushes send up “suckers” or new shoots
from the roots.
2. Some plants have roots that can produce new plants from
root pieces, such as sweet potato.
v. Leaves
1. Some houseplants produce little plants right on their leaves.
2. For example, African violets can produce plants from leaves
placed on top of the soil.
Processes Necessary for Plant Survival
1. Photosynthesis
a. Plants are organisms that make their own food, a simple sugar, for survival.
b. Photosynthesis: the process by which plants make sugar for food
c. Chloroplasts, found the in the cells of the leaf, contain chlorophyll, a
green pigment that absorbs light energy (sunlight)
d. During this process, plants use carbon dioxide gas from the air (taken in
through openings or pores, in the leaf called stomata) and water (taken in
through the roots) to make glucose (food) in the leaves.
e. During the process of photosynthesis, oxygen is also produced. The
oxygen is released into the air through the stomata.
f. Photosynthesis is the process that provides the oxygen in the atmosphere
that most living organisms need
2. Respiration
a. The food (glucose)created through the process of photosynthesis is used
to provide energy needed by plants to perform life functions
b. Respiration: the process that plants must break down the sugar in the cells
to obtain the energy from the food it produces
c. In this process, oxygen from the air (taken in through the stomata)
combines with glucose, which is then broken down into carbon dioxide
and water.
d. Energy is released. This energy can now be used by the plant to perform
life functions.
e. The carbon dioxide and water that are formed are then given off through
the stomata in the leaves.
3. Transpiration
a. Some of the water taken in through the roots is used in the process of
photosynthesis
b. However, plants lose most of the water through the leaves. This process is
called transpiration.
c. Without a way to control transpiration, plants would wither up and die.
Fortunately, plants are able to slow down transpiration.
d. Guard cells, mostly on the underside of the leaf, open and close the
stomata.
e. When the stomata are closed, water CANNOT escape from the leaf.
How Plants Respond to External Stimuli
1. Under certain conditions, when a mature plant or seed becomes or remains
inactive, it is said to be dormant.
a. Dormancy: a period of time when the growth or activity of a plant or seed
stops due to changes in temperature or amount of water
b. It helps to ensure that seeds will germinate when conditions are favorable
for survival of the small seedlings.
c. Example: leaves fall from trees prior to the conditions of winter and the
leaf buds do not open again until conditions are favorable in the spring.
2. Tropism: plants respond to changes in the environment by growing or moving
their stems, roots, or leaves toward or away from the stimulus.
a. Examples of Tropisms:
i. Phototropism: the way a plant grows or moves in response to light
ii. Gravitropism: the way a plant grows or moves in response to gravity
(also known as geotropism)
1. Stem and leaves grow up during germination
iii. Hydrotropism: the way a plant grows or moves in response to water
iv. Thigmotropism: the way a plant grows or moves in response to
touch
How Disease-causing Fungi Affect Plants
1. Fungi are a kingdom of organisms that do not make their own food
2. Many types of fungi must grow in or on other organisms, such as plants.
3. These fungi, for example grain mold, corn smut, and wheat rust, cause diseases
in those plants that result in huge crop losses.
4. Diseases caused by fungi may also affect other important crops, such as rice,
cotton, rye, and soybeans.
5. If a fungus infects a tree, fruit, or grass, it can eventually kill the plant
6. Fungi are also helpful:
a. As decomposers or breaking down dead plant and animal matter
b. As a source of medicine (penicillin)
c. As a source of food