Реферат: Discuss The Importance Of Plants On Planet

Earth Essay, Research Paper

`Plants As We See Them Plants are all

around us, renowned for their aesthetic appeal; their colours and structures

lend themselves to decoration. Plants are used in celebrations and commiseration?s

and are often celebrated in their own right- the annual Michigan potato

festival being a good example. ?Plants

are associated with national identity. The Scottish thistle; Irish Shamrock; Welsh

leeks and daffodils. Many national flags feature plants, the Cedar tree on the Lebanese

flag, and the Maple leaf on the Canadian flag. However all of these commendations

can not begin to celebrate the real importance of plants on planet earth. In

this essay I will explore the biological and physical importance of plants and

the issues surrounding them. The Real ImportanceFor

millions of years the chemical needs of the biosphere have run on solar energy.

Plants (along with some bacteria and green algae) are autotrophs that have the

ability to convert this solar energy into chemical energy by a process called

photosynthesis. This chemical energy, stored in plants is the fuel that

sustains life. PHOTOSYNTHESIS: The Light Reaction. Photosynthesis takes place in the leaves of plants. There

are two stages; the light-dependant or light reaction and the light-independent

or dark reaction. In photosynthesis the light reaction, for which the presence

of chlorophyll (the green pigment found in the chloroplasts) is essential, begins

with the absorption of sunlight in the blue and red wavelengths. The light is

absorbed by one of the numerous light harvesting areas found in the thylakoid

membranes, structures present in the grana. In the light reaction energy is

converted into ATP and NADPH. Water, obtained through the roots and stem of the

plant, is split, and as a by-product, Oxygen in released. This ?by-product? has

a major impact on the bioshpere. Today’s atmosphere would not have 21% oxygen

if it were not for photosynthesis. ? The Dark Reaction Also found in the

chloroplasts is a fluid filled region called the stroma. This structure

contains most of the enzymes needed for the light independent or dark reaction,

the process that converts Carbon Dioxide to Glucose. The dark reaction depends on

the ATP and NADPH obtained from the light reaction. Carbon dioxide obtained by

the plant from the atmosphere through the stomata in the leaves, bonds with Hydrogen

and Oxygen from the water and from the atmosphere to form carbohydrates in the

form of glucose (C6H12O6+6O2). The carbohydrates, stored in the leaves of plants,

makes them a valuable foodstuff for humans and animals. Situated near the

bottom of the food chain plants nourish our food, the herbivores we breed to

eat, and us. Roots The

roots of plants, hidden from view by soil also play a very important role in sustaining

life on planet earth. It is the roots of a plant that remove water and nutrients

from the soil, both essentials for photosynthesis. Plant roots break up rocks, which become part of new soil and roots

loosen the soil, allowing oxygen to penetrate. This benefits ground dwelling organisms,

such as shrews, rabbits and earthworms that all have their part to play in the

ecosystem. Botanical Industry Arable farming,

particularly in parts of Scotland, is a main provider of employment and a main contributor

to local economies. The vast majority of our fruit and vegetables are grown on

a farm somewhere in the world. The ability to grow and control the growth of

plants is essential, particularly to those in the third world who may have no

other source of income or indeed, food. Controversial Plants Genetic Modification is a phrase that strikes fear in to

the hearts of ?environmentalists? and Liberal Democrats alike. Genetic

modification of plants took place in its very simplest form even before Gregor

Mendel started tinkering with Peas in 1857. Perhaps this is the way forward?

Better disease resistance, larger crop yields anti-carcinogenic carrots; these

are all good things. I certainly look forward to slice-of- bread shaped tomatoes. In the future perhaps technology and botany can

combine in perfect harmony, if it is wise to do so. It was thought wise by

technologists to disregard the dietary preferences of herbivores, resulting in

B.S.E and subsequently vC.J.D.Plants In Medicine Many

plants have medicinal uses. Aspirin, from the bark of the Willow tree, is a

widely used and important drug. Aloe Vera, a succulent plant has many health

applications. More recently rubber plants have been genetically modified to

produce sap containing the human serum albumin, an essential nutrient used to

treat those who are critically ill. It is amusing to think that the health

properties of many plants, St. Johns Wort, hailed as a new wonder remedy for

depression and Peppermint, an aid for digestion, are at present viewed as the

big new thing. For centuries people relied on plants and their various

properties to cure illness and maintain good health, until they were shunned in

favour of ?conventional medicine?In Conclusion Plants are all around

us. Medicinally we are turning to plants (again!) to provide remedies for the

stresses and strains of modern living. Plants provide income and food. Yet few

of us stop to consider their real importance. Seen mainly as decorative

organisms, not often given credit for providing oxygen and food without which

there would be no life on earth. Genetic modification would appear to be a

positive step. Plants, as wonderful as they are, need to keep up with the times;

we demand more from our flora. Providing oxygen for us to breathe and food for

us to eat simply isn?t enough anymore.?