Definitions [10]
Define the following:
Respiration
Respiration: Respiration is a chemical process that takes place in all living beings (slow in plants). In this process, oxygen present in inhaled air reacts with the digested food material in the body. This results in the release of energy, carbon dioxide, and water.
Sugar + Oxygen → CO2 + Water + Energy.
Define rusting?
Rusting: Slow conversion of iron into its hydrated oxide in the presence of moisture and air is called rusting.
The envelope of air around the Earth is called the atmosphere. It is composed of nitrogen, oxygen, water vapour, and carbon dioxide, with other gases present in small quantities. The atmosphere is like a protective blanket that keeps our planet safe and helps support life.
Define the term Global warming.
Global warming : An increase in the percentage of carbon dioxide, methane, nitrous oxide and chlorofluorocarbon traps the heat causing the temperature of the earth and its surroundings to rise. This is known as global warming.
Define the following:
Combustion.
Combustion: Combustion also called burning “is burning of substance in the oxygen of air completely producing heat and light is called combustion.”
Define the term smog.
Smog : Oxides of nitrogen form a mixture of smoke and fog known as smog which affects our eyes too.
Define the term acid rain.
Acid rain : When sulphur trioxide and nitrogen oxide present in the air mix with rainwater they form sulphuric acid and nitric acid respectively. Rainwater containing these acids is called acid rain.
Define the following term:
Photolysis of water
Releasing electrons and dividing the water molecule (H2O) into its two components (Hydrogen and Oxygen). Photolysis is the term used to describe this reaction, which is characterised by the fracturing of molecules by light (photo = light, lysis = breaking).
Photosynthesis is the process by which living plant cells, containing chlorophyll, produce food substances (glucose and starch) from carbon dioxide and water by using light energy. Plants release oxygen as a byproduct during photosynthesis.
Define Photosynthesis.
In the presence of chlorophyll, photosynthesis is the process by which green plants and certain other organisms convert carbon dioxide and water into glucose (a form of sugar) using light energy, typically from the sun. As a byproduct, this process generates oxygen.
Chemica Equations [1]
The balanced chemical equation is: \[6\mathrm{CO}_{2}+12\mathrm{H}_{2}\mathrm{O}\frac{\text{light energy}}{\text{chlorophyll}}\mathrm{C}_{6}\mathrm{H}_{12}\mathrm{O}_{6}+6\mathrm{H}_{2}\mathrm{O}+6\mathrm{O}_{2}\uparrow\]
Key Points
- Photosynthesis mainly occurs in mesophyll cells (palisade and spongy) of leaves, using chlorophyll to trap sunlight.
- Carbon dioxide enters the leaf via stomata by diffusion down a concentration gradient.
- Water is absorbed by roots, transported via the stem to mesophyll cells of the leaves.
- Using light energy, chlorophyll helps synthesize glucose (C₆H₁₂O₆) from CO₂ and H₂O, releasing O₂ as a by-product.
- The balanced chemical equation is: \[6\mathrm{CO}_{2}+12\mathrm{H}_{2}\mathrm{O}\frac{\text{light energy}}{\text{chlorophyll}}\mathrm{C}_{6}\mathrm{H}_{12}\mathrm{O}_{6}+6\mathrm{H}_{2}\mathrm{O}+6\mathrm{O}_{2}\uparrow\]
