The smallest cell is Mycoplasma (PPLO-Pleuro pneumonia like organims). It is about 10 micrometer in size. The largest cells is an egg cell of ostrich.

Ploughing can promote the growth of earthworm in the field. The loose soil helps in the growth of worms and microbes present in the soil as they help in turning and loosening of soil.

In large fields,wheat and paddy crops are cut by a motorised machine called harvester. Harvesting is either done manually by a sickle or by a machine called harvester.

Yeast is used in making alcohol and wine because it is capable of converting sugar into alcohol. The sugar for making alcohol comes from the substances such as cane juice and fruit juices, or from substances like barley, maize, rice, etc.

The process of conversion of sugar into alcohol by the action of yeast is called fermentation.

The 5 R's – Refuse, Reduce, Reuse, Repurpose, Recycle. Refuse, Reduce, Reuse, Repurpose, Recycle – Five actions that can make your organization and you a better steward.

Aluminum reacts with oxygen to form a layer of aluminum oxide
4Al+ 3O₂ {tex}\rightarrow{/tex} 2Al₂O₃.

The process of fermentation involves breaking down of large molecules into simpler ones in presence of enzymes.
In India, ethanol is mainly prepared by fermentation of molecules a dark brown coloured group left after crystallization of sugar.
{tex}\mathop {{C_{12}}{H_{22}}{O_{11}} + {H_2}O}\limits_{Maltose} \xrightarrow[{(from\;yeast)}]{{Maltase}}\mathop {2{C_6}{H_{12}}{O_6}}\limits_{Glu\cos e} {/tex}
{tex}\mathop {{C_6}{H_{12}}{O_6}}\limits_{Glu\cos e} \xrightarrow{{Zymase}}\mathop {2{C_2}{H_5}OH + 2C{O_2}}\limits_{Ethyl\;alcohol} {/tex}

In order to provide food for a large population— regular production, proper management and distribution of food is necessary.

Reduce means to use a material/commodity in lesser quantity,.
e.g electricity and water

Recycle means a material that is used once is collected and sent back to a manufacturer so that they can make some other useful material from it. 
e.g., plastic cups and buckets, glass tumbler, paper, metal objects.

Reuse means using a thing over and over again instead of throwing it away. It does not involve the process of recycling either in small or large scale.
e.g., used envelopes, plastic carry bags, bottles of jam.

The over-use of chemical fertilizers can lead to soil acidification because of a decrease in organic matter in the soil. Nitrogen applied to fields in large amounts over time damages topsoil, resulting in reduced crop yields. Clay soils have an ability to buffer the effects of excess chemical fertilization.

Because of following reasons
1.  Not all products are created equally and many organic products produce inconsistent results.
2. Nutrient Levels Are Low
3. While you can produce your own compost, it’s a messy and complicated process that often leads to an inconsistent product and end-result.
 

Puberty is the time in life when a boy or girl becomes sexually mature. It is a process that usually happens between ages 10 and 14 for girls and ages 12 and 16 for boys. It causes physical changes, and affects boys and girls differently.

Puberty:  It is the time during which there occur sexual and physical changes which allow the transition of a child to an adult. Puberty starts at the beginning of adolescence. The onset of puberty starts much earlier in girls, between 8 and 13 years of age, whereas it starts between 10 and 14 years of age in boys and lasts upto 2 to 4 years.

Effects of using fertilizers –

• Effect on soil quality – Continued use of fertilizers leads to a loss of organic matter, a deterioration of soil structure.
• Eutrophication – Excessive use of fertilizers build up nitrates on the soil.

Nitrates and phosphates are washed by rain and carried to lakes, ponds and rivers and causes excessive growth of plants of algae. Algae deplete the oxygen content of the water body making it dead for other animals.

Due to continuous rain, the soil gets water logged. In water logged soil, there is deficiency of oxygen. Thus, the roots of plants do not get enough oxygen to respire and ultimately die out. Roots are responsible for absorbing minerals from soil which is essential for plants to survive. So, once the roots die out, the plants do not survive.

The scientific principles and the physical and chemical processes that are applied to obtain pure metals from their ores are known as metallurgy.
In other words, the process used for the extraction of metals in their pure form from their ores is referred to as metallurgy.

The process of extracting metal ores buried deep underground is called Mining. The metal ores are found in the earth’s crust in varying abundance. The extraction of metals from ores is what allows us to use the minerals in the ground! The ores are very different from the finished metals that we see in buildings and bridges. Ores consist of the desired metal compound and the impurities and earthly substances called Gangue. The extraction of metals and its isolation occurs over a few major steps:

• Concentration of Ore
• Isolation of metal from concentrated Ore
• Purification of the metal

Aluminium:

• Bauxite                                          AlO_x(OH)_3-2x [where 0 < x < 1]
• Kaolinite (a form of clay)          [Al₂ (OH)₄ Si₂O₅]

Iron:

• Haematite                                     Fe₂O₃
• Magnetite                                      Fe₃O₄
• Siderite                                          FeCO₃
• Iron pyrites                                   FeS₂

Copper:

• Copper pyrites                               CuFeS₂
• Malachite                                        CuCO₃.Cu(OH)₂
• Cuprite                                            Cu₂O
• Copper glance                                Cu₂S

Zinc:

• Zinc blend/Sphalerite                   ZnS
• Calamine                                         ZnCO₃
• Zincite                                              ZnO

Frequent and inappropriate use of antibiotics can cause bacteria or other microbes to change so antibiotics don't work against them. This is called bacterial resistance or antibiotic resistance. Because of antibiotic overuse, certain bacteria have become resistant to even the most powerful antibiotics available today.

Due to presence of insoluble calcium carbonate

Leguminous plants bears nodules in their roots. These nodules contain nitrogen fixing bacteria, which converts atmospheric nitrogen into soluble form and adds it into the soil and thus increases the fertility of soil.

Force = Pressure X Area
Then, F = 15 X 5 = 75 N

• He did not use good quality seeds.
• His field was not well irrigated.
• Manures/fertilisers were not properly applied.
• Weeds were not removed.

its solid state because the molecules inside a solid substance are very close to each other which results in higher density. Because the molecules of solids are closely pcked and have very little intercellular spaces