Science Focus Topic 1 Notes: People and Plants | Print |

People use plants for things other than food. Plants also provide fibre, which is the tissue of plants from the stem, leaves, seeds or roots. The subtopics will outline how plants frovide food and fibre for human needs.

Plants in the Environment

As a critical part of the ecosystem, plants provide oxygen for organisms to survive. They are able to reduce the problem of pollution, by using carbon dioxide. Plants are also the basis of most food webs as producers of food for herbivores and ultimately carnivores. Plants also provide shelter for animals, clean and filter water and help prevent soil erosion.

Plants for Food

Nearly 75% of the the world's food supply is based on seven major crops: wheat, rice, maize (corn), potatoes, barley, cassava and sorghum.

From Plant to Final Product
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Chocolate is made from the fruit of the cocoa tree

78% of vegetable oil production is from canola

contains iodine and is used in soup broths and sushi

half of the world's sugar comes from sugar beets, located in the sugar beets' roots

Cocoa beans are roasted, shelled and then crushed. Cocoa butter and cocoa powder are separated. Cocoa powder is then mixed with milk to make chocolate.

Canola is pressed from the canola seeds and used as salad oil and frying oil

other products from seeweed include: ice cream, chocolate milk, yogurt, whipped cream, pies, jellies and candies

roots are shredded, heated in running water and the concentrated clear liquid crystallizes to produce sugar similar to sugar cane

It is used to make margarine, shortening, baked goods, potato chips and french fries

seeweed products are often used to thicken food (alginate, agar, carrageenan)

Plants for Fibre

Plants provide fibres for clothing, paper and shelter. The aboriginal people from the west coast wove cloth from the bark of the western red cedar tree. Much of our clothing today comes from synthetic (manufactured) material, such as polyester and nylon. Natural fibres also provide resources for cloth:

Cotton - is a natural fibre that absorbs moisture and then allows it to evaporate easily, making it the world's most important non-edible plant. The cotton fibres come from the plant's seeds. The silky fibres are strong, flexible and have a gradual spiral that causes the strans to intelock when twisted, making them ideal for spinning into thread. The second layer of fibers are shorter and are 'fuzzy' - they are used to make cotton batting, rayon and various types of plastic and paper.

Hemp - Early makers of jeans used hemp, which is the oldest cultivated fibre plant in the world. Other products included the Bible, sails and ropes. Hemp has a less negative effect on the environment, because it uses less land area than trees, can be harvested in a year, lasts longer than paper, can be recycled up to seven times, chokes out weeds naturally and is not prone to insect pests.

Flax - is a food and fibre crop. The flax fibres, which are smooth and straight, are taken from the stem of the plant are are two to three times stronger than cotton fibres. Flax fibre is used for making linen paper, linseed oil - which is used as a drying oil in paints and varnish - and in products such as klinoleum and printing inks.

Plants for Medicine

An apple a day keeps the doctor away! Many medicines (over 7000) contain ingredients made from plants. Herbal remedies are a common example of how plants are used to prevent illness.

Plant medicines include:

  • tea (made from ginger root) - is used to soothe an upset stomach
  • white willow bark - is used to ease pain
  • opium poppy's seed pod - thick milky fluid provides a powerful pain medication - morphine
  • codeine is also found in the poppy - it is used in cough medicines
  • quinine - which comes from the cinchona tree - is used to prevent malaria.

Plants for Transportation and Construction

Rubber is one of the most important plant products that people use. Natural rubber comes from the Brazilian rubber tree. Synthetic rubber is made from coal and oil by-products - but natural rubber is also an important ingredient.

Canoes were carved from trees by Aboriginal people. Lubricants are provided from coconut and castor bean oils. The construction industry in North America uses wood (softwood lumber from British Columbia) as a building material.

Plants for Fuel

Wood or coal (which is a fossil fuel) are used to heat homes. Sugar can be turned into ethanol and wood can provide methanol (wood alcohol). Fuel from plants is economical, but not energy efficient, because a large amount of energy is need to grow the plants and a lot of the energy is lost when it is converted to fuel.

Human Needs and Plant Needs

Our task is to make sure that plants survive and thrive in order to have this important resource in the future.

Topic 1 Review p. 103