UNIT B - Plants for Food and Fibre Review

UNIT B - Plants for Food and Fibre Review

Section 1.0

Understanding structures and life processes of plants helps us to interpret their needs

1.1The Body of Seed Plants

seed plants are those plants that make seeds. e.g. daisies, wheat, orchids.
largest group of plants in the world.

Each Plant Structure Has A Function

(refer to figure 1.2, p.101)

Flowers: contains both the female and male parts for reproduction
Leaves:produce food for the plant, take in and release oxygen and carbon dioxide, allow water to exit the plant.
Stem:provide a pathway for movement of water and food, support leaves and reproductive structures.
Seeds:contain an embryo that will form a new plant, contain a food supply for the embryo.
Roots:absorb water and dissolved nutrients, anchor the plant in soil.

1.2Plant Processes

A Process for Moving Water Up From the Roots

Water moves up a plant from the roots using the following processes:

1. Transpiration - evaporation of water from the surface of the plant, mainly the leaves. It is the main process that draws water.Water particles evaporate from the surface of the leaves. This causes more water to be drawn up to the leaves and end up on the leaf surface.

2. Capillary Action - water travels from the roots to the leaves through small tiny tubes inside the roots and stem. Water molecules are naturally attracted to each other and stick to one another. With the attraction of the water particles to each other and to the sides of the tubes, the water moves up wards inside the plant.

3. Osmosis - when the concentration of water in the soil is greater than the concentration of water in the roots of a plant, water moves into the root cells.

A Process to Make Food

plants make their own food through a process called PHOTOSYHTHESIS. This process uses light energy, carbon dioxide and water to produce sugar (glucose) and oxygen.
photosynthesis takes place in structures inside the leaf called CHLOROPLASTS. The chloroplasts captures the sun's energy.

A Process to Use Food

CELLULAR RESPIRATION - plants use the sugar (glucose) produced in photosynthesis for food and oxygen to produce water and carbon dioxide (as waste) and useful energy.

Processes to Move Substances In and Out of Plant Cells

food produced from photosynthesis must be transported throughout the plant as well as getting rid of the waste products.

(refer to p. 106, fig. 1.9)

A plant cell is surrounded by a membrane that has pores ( tiny openings). Some substances are able to move in and out through these pores. The cell membrane works as a filter - some substances may pass through while others remain inside the cell.

Processes used to transport materials

1. DIFFUSION - occurs when there is a difference of concentration of particles on either side of the membrane. the flow is always from an area of high concentration to an area of low concentration.

2. ACTIVE TRANSPORT - uses energy to move a substance in and out of plantcells.

3. OSMOSIS - movement of water particles through a membrane. Again the flow isfromhigh to low concentration.

A Process to Exchange Gases

many processes require gases in order to produce food or transport substances. GAS EXCHANGE is the process of these gases entering and leaving the plant.
oxygen and carbon dioxide diffuse through tiny openings in the leaf

1.3Reproduction of Seed Plants

The Life Cycle of Seed Plants

(refer to fig.1.15, p.110)

a life cycle is the stages that a living thing passes through to go from one generation to another.
SEED STAGE - the seed has three main parts: embryo, stored food and a seed coat. The stored food surrounds the embryo in some species while inothers, the stored food is part of the embryo. This food is used until the plant begins to photosynthesize and produce its own food.
SEEDLING STAGE - at this stage plants grow very fast and produce new leaves, roots and stems. Seedlings produce their own food but also require nutrients from the surrounding soil.
ADULT STAGE - a plant reaches this stage when it produces reproductive structures. In seed plants this would be a flower or cone.

Reproduction of Seed Plants

POLLINATION - a process where the male and female parts of a plant join to make a seed.
POLLEN (MALE) -. Pollen grains are small, sticky cells. One plant produces millions of pollen grains.
OVARY (FEMALE) -. The ovary contains the OVULE.
Process - a pollen grain lands on the stigmaof a flower, above the ovary pollen grain produces a pollen tube that grows down from the stigma called the style. The style leads to the ovary which holds the ovule. Cells transfer from the grain to the ovule, the ovule grows into a seed.
cone bearing plants usually have separate male and female cones. Once pollinated, the seed develops on the female ovule.
POLLINATORS - organisms that carry pollen from one flower to another. examples: birds, insects, bats.
the organisms enter the flower looking for nectar and become coated with pollen and transports it to the next flower.

Reproduction Without Seeds

VEGETATIVE REPRODUCTION - reproduction of plants without seeds. plants produced this way are genetically identical.
RUNNERS - long stems that grow along the surface of the soil. RHIZOMES - new stems produced underground.
SUCKERS - some produce from new roots.

Technology to Reproduce Plants

CUTTINGS - small pieces of a plant that usually have a part of the stem and a few leaves.
GRAFTING - attaching a part of one plant to another usually a small branch. Eventually the two sections will grow together.

1.4Plant Structures are Adapted to Their Environment

Plants are Adapted to Their Environment

Examples of adaptations:

Dry Areas - plants must conserve water. Cacti have thick stems because they store water in them. The tiny spines protect the water from predators.
Grasses - have narrow, thin leaves so that a number can be accommodated in one area and assist in pollination by the wind. The depth of the roots changes with the moisture or lack of moisture.
Sunflowers - have large leaves to attract the sun and produce bright, large flowers to attract insects that are vital in the pollination process.
White Spruce trees - thin, needle-like leaves with a thick resin coating that protects the plant from drying out.
Fibrous roots - thick mat just below the surface that gathers water at the upper layers of soil.
Tap roots - long roots that reach water deep down where others can't reach. Short growing seasons - wild mustard can produce seeds in less than two months.

1.5Plant Needs and Growing Conditions

all plants need the right amount of light, water, nutrients and space to survive.
LIGHT - need light in order to carry out the process of photosynthesis.Not all plants need the same amount of light; some require shade more than direct sunlight.
WATER - plants will die if they do not get enough water and if they get too much water.
NUTRIENTS - substances that provide the energy and materials that plants require in order to grow. They include nitrogen, phosphorous, potassium, calcium and magnesium.
SPACE - based on the size and needs of a plant.

Section 2.0

Plants Play an Essential Role in the Environment and in Meeting Human Needs

2.1The Role of Plants in the Environment

plants provide the following: oxygen, shelter, food, build and protect soil, are a link in the food chain

2.2We Use Plants in Many Ways

aboriginal people used plants for food, fibre and medicines.
fibre from plants can be used for clothing, building materials, paper products.
plants are still used in medicines.
also used to make rubber and glue, perfume fragrances, dyes in paper.

2.3Managing Living Resources

LIVING RESOURCES are living things that can be used for human needs. the first people to use living resources were the aboriginal people. They used the plants for food, fibre and medicines as well as practicing methods to encourage plant growth such as clearing areas using fire.
with the introduction of rifles, the aboriginals became less dependent on plants since they were now able to kill animals with greater ease.
the European settlers began to clear and farm land therefore bringing management of resources to the forefront.

Soil is an Important Resource that Human

Activity can Protect or Degrade

3.1What is Soil?

Soil Contains Minerals and Organic Matter

soil has mineral and organic particles. The mineral particles are made from rock that has been broken down. Mineral particles makes spaces in the soil that water can run through quickly.
organic particles are made from plants and animals that were once living. When partly decomposed the material is called HUMUS.
Humus provides plants with the nutrients they need and also absorbs water.

Characteristics of Sandy Soil

sandy soil runs through your fingers and has few lumps. when wet and compressed, the soil will not stay together. light brown in colour.
most particles are minerals and very little humus.
does not contain much food for plants and dries quickly because water runs through it very fast.

Characteristics of Clay Soil

clay soil feels slippery when moist and rubbed between your fingers. if wet it will stick together and form a tight ball.
dry clay is very hard. the colour varies.
most particles are minerals and very little humus. The particles are very small and give the clay a fine texture.
the pore size is also small therefore the clay can hold water and nutrients but air cannot penetrate since most of the air spaces can be filled with water.

Characteristics of Loam Soil

loam soil is crumbly almost like a moist cake.
when squeezed it will form a loose ball and is not sticky. loam soils are dark brown or black.
has a balance between the amount of organic and mineral particles. will absorb enough water to stay moist .
has plenty of nutrients for plants to use. i.e. good for growing most plants.

3.2Our Practices Can Improve or Degrade Soil

Fertilizer Use

soil nutrients can be provided by fertilizers.
organic fertilizers are made from plant and animal waste.
chemical fertilizers are mixtures of types of chemicals that promote plant growth. Potash is used to increase potassium; urea and ammonia increase nitrogen.
too much fertilizer can damage plants, pollute water and the soil.

Irrigation

used in areas where there is little or no rain.
helps farmers ensure that the plants get enough moisture at the right time of their growing cycle.
requires careful management.
can dissolve nutrients that can damage plants.

Clearing the Land

clearing land allows farmers to plant seeds and decreases the amount of competition between plants.
involves removing most of the plant cover and plowing under anything that remains.
can result in the loss of valuable topsoil if not managed properly.

Plowing Changes Soil

the process of cutting into the soil and turning the top layer over.
breaks up soil creating more air spaces and making it less compacted.
farmers protected the topsoil by leaving stubble on the field to prevent wind erosion.

Crop Rotation Helps to Keep Soil Healthy

practice planting a different crop in a particular field every year.
plants that are rotated must be matched according to their nutrient needs.

The Ways That Plants are Grown and Used are Related to Human Needs, Technology, and the Environment.

4.1Modifying Environments to Increase Yields

YIELD - the amount of useful plant part per plant
use pesticides, herbicides, fertilizers, etc. to increase yields.
sometimes we use artificial environments such as greenhouses and hydroponics systems to increase yields.

4.2New Plant Varieties are Developed by Selective Breeding

SPECIES - a group of organisms with similar traits that can reproduce with each other.
VARIETY - is a subset of a species. A variety has specific TRAITS that distinguish it from other varieties.

Varieties Are Developed by Selective Breeding

SELECTIVE BREEDING - the process of selecting plants with specific traits and reproduce them.
GENETIC ENGINEERING - a process in which single genes are added to a plant's cell.
GENE - is a tiny piece of material in a cell's nucleus. Each gene is responsible for the inheritance of certain traits or characteristics. genes can come from different plants or from totally different living things.

New Varieties Can Cause New Problems

may require more fertilizer or special treatment.
increase use of pesticides.

4.3Controlling Weeds and Pests

Controlling Weeds With Herbicides

HERBICIDES - chemicals that kill plants.
homeowners use herbicides to kill weeds in flower beds and lawns while farmers kill weeds and selected plants in order to grow one type of crop.
problems: some weeds are a food source for other living organisms and killing these plants may kill the organisms.
a build up of herbicides can damage the soil and make it less fertile.
herbicides that get into the water can cause damage to the ecosystem.
some weeds can become resistant to the herbicide after long periods of use.

Controlling Insects With Pesticides

PESTICIDES - substances that kill insects.
farmers kill insects harmful to their crops and at the same time may also kill those needed for pollination.
used carefully, they can increase the yield of a crop.
as with herbicides, long use of pesticides can result in insects becoming resistant to the product.
many foods have traces of the pesticide on their surface and so it is a good practice to wash fruits and vegetables before eating them.

Biological Control

BIOLOGICAL CONTROL- the use of a natural predator to control a pest.
the predator does not eliminate the pest but rather changes the balance so that there are fewer of them.
takes a while to work and is not effective for large scale operations.

4.4Consequences of Environmental Management

UNINTENDED CONSEQUENCE - results of an action that were not predicted or planned.
often occur when we do not have all the facts.

ENVIRONMENTAL MANAGEMENT - balancing the needs of humans with the needs of the environment.
can involve many different technologies and ways of using resources.

MONOCULTURE - the practice of growing only one type of crop in a large area.
cuts down on costs and fertilizer use, easier to harvest.
Disadvantage - can give pests a huge food supply resulting in a population explosion of the pest.
reduces BIODIVERSITY - the number of different species of the environment.