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Sharpen Your General Knowledge
Shamim Ansary:
What Sea Creatures Plant Their Own Gardens?
The spider crab not only plants its own seaweed garden, but it plants the garden right on its own body! This crab snatches pieces of seaweed, cuts them into smaller pieces, and attaches the cuttings to the hairs on its legs and shell.
The seaweed cuttings take root on the crab, and eventually grow to completely cover it. By the time the spider crab is finished with its garden, it looks just like a mass of seaweed, and is perfectly hidden from its enemies.
Another kind of crab, the coral-gall crab, collects small sea creatures called corals and places them all around its body. As a coral grows, it surrounds itself with a shell, and when it dies, the shell remains.
So the coral-gall crab soon finds itself surrounded by a coral shell, with small holes in the shell where the corals once lived. These holes permit water and food particles to reach the imprisoned crab.
So while the coral shell protects the crab from its enemies, the crab can never escape from its shell. It spends the rest of its life locked inside the coral, and may even give birth to young crabs inside the shell!
Shamim Ansary:
What Plant Is Really Two Plants In One?
You may have seen the small, moss-like plants called lichens covering rocks or the branches of old trees. Though you’d never guess it from looking at these plants, lichens are really two plants in one: a fungus and an alga.
The fungus and alga in a lichen live so closely together that you’d need a microscope to tell them apart. The relationship of this fungus and alga in a lichen is called symbiotic, which means that both the fungus and alga help each other survive.
The lichen’s fungi send branchlike pieces into rocks or pieces of wood from which they absorb moisture and minerals. The algae make food by photosynthesis, the process that all green plants use to make food from sunlight, minerals, and water.
So, the fungus “waters†the alga, and the alga “feeds†the fungus.
Shamim Ansary:
How Much Oxygen Do Plants Consume at Night and How Is Sleeping With a Live Plant Dangerous?
There is just a grain of truth in the idea, as green plants do absorb some oxygen for use in respiration, the mirror image of photosynthesis.
Photosynthesis can occur only when there is light, so at night plants are absorbers of oxygen, on balance.
However, true danger would result only from an extremely large body of plants in a very tightly closed sleeping chamber with a very limited supply of oxygen.
Another person in a room would be a far heavier oxygen consumer than one plant.
These principles of gas exchange in photosynthesis and respiration were explored in the late eighteenth century by Jan Ingenhousz, a Dutch botanist.
Once Joseph Priestley had discovered oxygen and plants’ role in producing it from carbon dioxide, there was a great vogue for putting flowers in sickrooms to “purify†the air.
Ingenhousz was skeptical about the benefits.
His experiments showed that only the green parts of plants add oxygen, and then only if placed in strong light; flowers and other non-green parts, as well as green leaves left in darkness, used up oxygen just as animals did, he found.
In aerobic respiration, plants use free oxygen, usually from the air, for chemical reactions that release energy from organic substances; sugar and oxygen react to produce carbon dioxide, water and chemical energy.
In photosynthesis, carbon dioxide and water react in the presence of light energy to produce sugar and oxygen.
During the day, both processes occur, but photosynthesis proceeds more rapidly than respiration, and the carbon dioxide produced is immediately used in photosynthesis.
Excess oxygen from the photosynthesis escapes into the air.
At night, however, photosynthesis ceases and respiration continues, so that green plants are absorbing oxygen and producing carbon dioxide.
Shamim Ansary:
How Do Coal and Oil Produce Energy?
Millions of years ago, when much of the earth was a swampy forest, billions of plants and animals died and fell into the shallow water.
The oxygen, hydrogen, nitrogen, and carbon in these living things were acted upon by bacteria and pressure over thousands of years, freeing gases from the decayed matter and leaving behind only the carbon.
Coal and oil are made up mainly of carbon. The difference is that coal was under more pressure as it formed, and the carbon atoms arranged themselves in solid form.
When coal or oil burns, it combines with oxygen in the air, producing carbon monoxide and other gases. This chemical change produces a great deal of heat energy.
So when we burn coal or oil to heat or light our homes, or to heat water at electricity plants, we’re really burning the remains of plants and animals that lived ages ago!
Shamim Ansary:
Where Do Astronauts Get Oxygen for Extended Space Missions On the International Space Station?
However, when the space station built, plans were announced to have it carry equipment to recover oxygen indirectly from the carbon dioxide crew members exhale. astronauts
NASA’s Johnson Space Center tested means to recycle air and water used by volunteers sealed in an airtight chamber with a limited amount to breathe and to drink.
Mechanical and chemical means were being used to recycle all the air and water, including urine.
Past tests involved using wheat plants to recycle breathing air, and by 1997, sixty and ninety day tests using plants and/or physiochemical recycling were planned.
In a life-support system for the space station designed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, carbon dioxide is reclaimed from the exhaled air by a concentrator.
The 95-percent-pure carbon dioxide is burned with hydrogen in a carbon dioxide reduction device, yielding water and some waste products, either carbon or methane.
This water is used as drinking water on the space station.
Some water from the hygiene system, dirtier water, is put in an oxygen generator, an electrolyzer that breaks it down into its two components, hydrogen and oxygen, by electrolysis.
The oxygen is to be fed back into the cabin, closing the cycle.
The hydrogen is used in the propulsion system to keep the space station at the proper attitude and to reboost it into the proper orbit as the orbit decays.
Oxygen requirements are about 1.8 pounds per day per person. On past space flights, carbon dioxide was recaptured but not reused.
Initially, the Soviet Union used a multi-step chemical recovery system to obtain oxygen for its extended space flights.
But they switched to an electrolyzer-type process, with the supply vehicle, Progress, bringing up water that is then electrolyzed.
U.S. missions have also supplied breathable air.
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