NIOS Class 12th Environmental Science English Medium Solve Assignment (TMA) 2021

 Environmental Science (333)

Tutor Marked Assignment

Max. Marks : 20

1. Answer any one of the following questions in about 40-60 words.

(a) Name the discovery that enabled the primitive humans to colonise colder parts of the earth. Mention one more advantage that primitive humans derived from the discovery.

Ans- The discovery of fire had enabled the primitive human beings to move to the colder part of the earth This is because the fire provided them the desired temperature to adapt to the changing climatic conditions One More advantage that primitive humans derived from the discovery is making of tools enabled primitive humans to dominate and survive the wild condition prevailed in ancient era.

3. Answer any one of the following question in about 40-60 words.

(a) Rural and urban settlements differ from each other in many ways. Write difference between rural and urban settlements with reference to:

(i) Occupation.

(ii) Population density.

Ans-

4. Answer any one of the following question in about 100 to 150 words.

(b) A dairy farm owner gives harmonal injection to his livestocks (Milching animals) in order to facilitate to increase milk production. Name the chemical injected and also mention its adverse effects on the livestocks.

Ans- Sometimes referred to as Bovine Somatotropin (rBST). the bioengineered hormone is injected in the cows every other week to force the cows to produce more milk than their bodies normally would. BGH is similar although not identical to a hormone that the cow naturally produces.

5. Answer any one of the following question in about 100-150 words.

(b) What is the importance of environmental ethics in our lives? Explain in four sentences.

Ans- 

Explanation:

Environmental ethics: The field of environmental ethics generally concerns human beings ethical relationship with its natural environment a much debated topic in history has gathered the top spot in the 21st century. Various international commitments has been registered in this century like Paris Agreement, Monteral protocol , Kyoto Protocol has proven to be worth its name. Environmental ethics has formed the subject of basis from the developed countries to the developing countries.

6. Prepare any one project of the following projects given below.

(a) Obtain mushroom seeds and grow mushrooms, prepare your own compost and spawning. Make observation on the growth of mushroom culture and note the time taken till ready of mushrooms. At the end of doing this, write a brief report. You can take help from internet as well as your elders.

Ans- in the early years of mushroom culture in the Netherlands, compost was scooped into the mushroom trays and then inoculated with spores A nine week wait followed, until the mycelium spawned sufficiently flushing started and the grown mushrooms could be harvested by hand.

The cultivation process hasn’t changed that much, but the way the Successive steps are performed differ immensely. Hardly anything is done by hand anymore in modern mushroom farming. These changes started to take place when three young mushroom growers from Mook set up the “Cooperatieve Nederlandse Champignonkwekersvereniging (Cooperative Dutch Mushroom Growers Association: CNC) in 1453. One of their activities was to organize the preparation of compost, resulting in the delivery of ready prepared compost permeated with spawn to most mushroom growers doors Mushroom cultivation can be divided into five phases:

Phase 1: Composting

The growing cycle of mushrooms starts with compost. Compost preparation starts with horse manure. The compost factories get the horse manure from large horse breeding companies that pay the compost factories to collect the manure. Straw, gypsum, chicken manure and water are added to the horse manure. The straw improves the structure, gypsum ensures the proper acidity and the two manures are the nutrients. The compost is produced in tunnels in order to prevent the smell from becoming a nuisance. As manure emits ammonia, compost factories purify the air with ammonia wash to prevent the emission of gases. The indoor fresh compost looks like earth from a forest. Dark brown, full of trampled bits of straw. The compost is steaming, due to the composting process: heat is generated which digests the components. What’s left is a very fertile, nutritious source for mushrooms. On one batch of compost, two to three flushes of mushrooms can be grown. A square metre of compost (which is equal to 9o kilos) yields a maximum of 35 kilos of mushrooms. After that it’s no longer lucrative to reuse the compost. The leftover compost can still be used as a soil conditioner in other agricultural companies.

The largest producer of mushroom compost in Europe is Walkro, with production facilities in Belgium, Germany and the Netherlands.

Compost – one of the most important basic materials for the mushroom Industry

Phase 2: Spawning

In a tunnel, the indoor fresh compost is pasteurized at 57-60 degrees Celsius. This kills all possible bacteria. The compost stays in the tunnel to mature for six days, after which the compost is mixed with spawn that will produce the mushrooms: the mycelium. The compost is then moved to another tunnel where the mycelium can spread through the compost. The mycelium grows quickly, after two weeks it has completely permeated the compost, which means that is has reached the point that it is ready for the growers. At this time the compost looks like light brown peat.

Most mushroom growers do not produce their own spawn, as it is a very sophisticated process. Specialized companies produce the spawn by inoculating grain with spores The grain is sterilized first to prevent infection and it’s kept moist, exactly the way mushrooms like it. Ten kilo of spores (22 pounds) provides about five hundred kilos of inoculated grain (1100 pounds). The grain is incubated in a bag for two weeks at 25 degrees Celsius (75 degrees Fahrenheit), then transferred to a Refrigerator at 2 degrees Celsius (35 degrees Fahrenheit) to harden it. In this way, the spawn gets a shelf life of 6 months without the miycelium losing its vitality.

The spawn of the mushrooms is in these tiny, white grains That’s why they are called “grain spawn”.

Phase 3: Casing

The matured compost is spread onto long stainless steel boxes, the mushroom beds. The beds are inside special dark rooms called cells. The temperature in the cells is kept nice and warm, at about 23 degrees Celsius A layer of peat casing material is added on top of the compost to keep the compost moist. Over a period of six days, 20 to 25 litres of water is sprinkled on cach 2 in each cell because more moisture is needed. After this, the fungus has two days to grow through the covering layer of casing soil.

Phase 4: Pinning

Mushrooms only grow in the wild in autumn However, they can be cultivated year round by recreating autumn conditions. Therefore, the temperature in the cell is gradually lowered from 23 to 17 degrees Celsius over four days. The mushroom grower starts to lower the temperature once he sees that the mycelium has grown to its full extent. The temperature shock is a sign for the mycelium to start sprouting the mushrooms. The same thing happens in nature Mycelium grows well in wild autumn weather, and after an October storm, the mushrooms will start appearing. The mycelium starts to form little buds, which will develop into mushrooms. Those little white buds are called pins. In this phase, air temperature and humidity can influence growth Low air temperature and low humidity produce more buds, which yield smaller mushrooms Higher air temperature and humidity produce fewer but larger mushrooms. 

The birth of a mushroom

Starting with mycelium, growing to pins and finally having a mushroom – here you can see the life of a mushroom

Phase 5: Harvesting

After this the temperature is kept steady at 18 degrees Celsius Mushrooms grow best at this temperature they will grow 3 cm (2 inch) in a week, which is the normal size for harvesting In weeks the first flush is harvested. Mushrooms destined for selling fresh are still harvested by hand, mushrooms destined for preserving are being picked and sorted mechanically. Although hand-picking is a lot of work, it offers the best guarantee that the mushrooms will be removed 

from the beds undamaged. On average, a picker can harvest between 18 and 30 kilos of mushrooms an hour. The mushrooms are picked from the beds with a rotating motion and sorted by the pickers based on quality, size and weight. Nine days after the first flush, the second flush will be harvested The second flush often consists of larger, but fewer mushrooms than the first flush.