فتوسنتز

فتوسنتز

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Photosynthesis

Did you know that plants can “eat” light? Green plants obtain their energy directly from the sun, by converting light energy into chemical energy. This process is called photosynthesis. Photosynthesis provides life not only to plants, but also to the animals (including people) that eat those plants. In addition, photosynthesis gives us the oxygen that we need to breathe. Scientists have gained detailed knowledge of the complex process of photosynthesis, which will be summarized only briefly here. The basic chemical reaction of photosynthesis involves the conversion of water, carbon dioxide, and light energy into glucose and oxygen.

Glucose is a form of carbohydrate that allows the storage of energy. It takes six molecules of carbon dioxide and twelve molecules of water to produce one molecule of glucose, with six molecules of water and six molecules of oxygen as by-products. How do plants obtain the water, carbon dioxide, and light energy that they need for photosynthesis to occur -Water is obtained through the roots of the plant, and is transported upwards through the stem or trunk of the plant to the leaves. The leaves can directly absorb carbon dioxide from the air. The leaves also contain a green-colored chemical, which is a pigment named chlorophyll. Chlorophyll has the special ability to absorb light energy from the sun, and convert that energy into chemical form.

The process of photosynthesis involves several steps. In the first stages, light energy is absorbed by chlorophyll. Some of this energy is used to decompose water molecules into hydrogen and oxygen. The hydrogen is used in the next steps of photosynthesis, and the oxygen is released into the air as a by-product. The remaining energy that is gained from sunlight is stored in chemical compounds that are also used in the next stages of photosynthesis. In those later stages, the hydrogen from the earlier stages is used, along with carbon and oxygen from carbon dioxide molecules, to create increasingly more complex molecules. This process uses the stored energy from the earlier stages of photosynthesis. Because this energy has already been obtained from sunlight, these later stages of photosynthesis do not require any additional light. The later stages of photosynthesis eventually produce glucose, which is a complex carbohydrate molecule.

Glucose allows energy to be stored in a stable form that can be used by the plant. Glucose molecules can be sent throughout the plant, to provide the energy that is needed for the plant to live, grow, and reproduce. If the plant is eaten by an animal, then the animal can use this energy for its own life processes. The process by which plants convert light into food is surely one of the miracles of nature. Photosynthesis is a fascinating and complex process, and it provides us with the food we eat and the air we breathe.

summarize

source 1
to give a summary of something (= a statement of the main points)
The results of the research are summarized at the end of the chapter.

Usage note: conclusionSumming up an argumentIn conclusion, the study has provided useful insights into the issues relating to people’s perception of crime.
Based on this study, it can be concluded that the introduction of new street lighting did not reduce reported crime.
To sum up, no evidence can be found to support the view that improved street lighting reduces reported crime.
The available evidence clearly leads to the conclusion that the media do have an influence on the public perception of crime.
The main conclusion to be drawn from this study is that public perception of crime is significantly influenced by crime news reporting.
This study has shown that people’s fear of crime is out of all proportion to crime itself.
Fear of crime is out of all proportion to the actual level of crime, and the reasons for this can be summarized as follows. First…
Overall/In general, women are more likely than men to feel insecure walking alone after

source 2
to make a short statement giving only the main information and not the details of a plan, event, report etc [= sum up]:
The authors summarize their views in the introduction.
to summarize To summarize, in most cases the schools were achieving the standards set.

briefly

source 1
in few words
Briefly, the argument is as follows…
Let me tell you briefly what happened

source 2
in as few words as possible:
Sonia explained briefly what we had to do.
[sentence adverb]
Briefly, I think we should accept their offer.

conversion

source 1
conversion (from something) (into/to something) the act or process of changing something from one form, use or system to another
the conversion of farm buildings into family homes
Conversion to gas central heating will save you a lot of money.
No conversion from analogue to digital data is needed.
a metric conversion table (= showing how to change metric amounts into or out of another system)
a firm which specializes in house conversions (= turning large houses into several smaller flats/apartments)

source 2
when you change something from one form, purpose, or system to a different one
conversion into The warehouse was undergoing conversion into apartments.
conversion of the conversion of waste into usable products
conversion to The British conversion to the metric system took place in the 1970s.
house/barn/loft etc conversion British English
(=when you change the use of a house, barn etc, so that it becomes apartments, a house, a room etc)

upwards

source 1
towards a higher place or position
A flight of steps led upwards to the front door.
Place your hands on the table with the palms facing upwards.
The corners of her mouth curved upwards in amusement.
Opposite: downwards

source 2
moving or pointing towards a higher position [≠ downwards]:
Pointing upwards, he indicated a large nest high in the tree.
The path began to climb steeply upwards.

pigment

source 1
a substance that exists naturally in people, animals and plants and gives their skin, leaves, etc. a particular colour
Haemoglobin is the red pigment found in blood.

source 2
a natural substance that makes skin, hair, plants etc a particular colour:
Melanin is the dark brown pigment of the hair, skin and eyes.
The artist Sandy Lee uses natural pigments in her work.

decompose

source 1
decompose (something) (into something) (technical) to divide something into smaller parts; to divide into smaller parts

source 2
to divide into smaller parts, or to make something do this

by-productsource 1
a substance that is produced during the process of making or destroying something else
When burnt, plastic produces dangerous by-products.

source 2
something additional that is produced during a natural or industrial process
by-product of a by-product of oil refining

miracle

source 1
an act or event that does not follow the laws of nature and is believed to be caused by God
Synonym: wonder

source 2
an action or event believed to be caused by God, which is impossible according to the ordinary laws of nature:
Do you believe in miracles?

fascinate

source 1
to attract or interest somebody very much
China has always fascinated me.
It was a question that had fascinated him since he was a boy.
The private lives of movie stars never fail to fascinate.

source 2
if someone or something fascinates you, you are attracted to them and think they are extremely interesting:
The idea of travelling through time fascinates me.