My Science School

A lot of things that are commonly used in commercial farming are prohibited in ecological agriculture. In ecological agriculture, fields are not sprayed with chemical pesticides, and artificial fertilizers are not added to the soil. Animals are raised in ways appropriate for maintaining the health of the species. For example, hens are not crammed inside cages for their entire lives. They mostly feed on grains grown organically. Moreover, all animals are fed with ‘organic food’. All these measures require a lot of space and time to be completely successful. Hence, organic products are mostly expensive. 

The 19th century saw the emergence of a general concern to protect the wonders of nature. The first protected areas were set up. The Yellowstone National Park, the world’s first protected area, was established in 1872 in the middle of the Rocky Mountains. Here, an attempt was made to retain the unique landscape along with the diverse flora and fauna. This idea was soon adopted by Canada, Australia, and New Zealand, who also converted extraordinary habitats into national parks or wildlife sanctuaries. Today, there are around 2200 national parks in 120 countries. 

The United Nations Educational, Scientific and Cultural Organization (UNESCO) is a unit of the United Nations that has taken up the task of protecting the natural wonders of the world. World heritage is classified into cultural and natural heritage. Cultural heritage signifies important cultural sites, such as the pyramids in Egypt; natural heritage signifies natural wonders such as the Great Barrier Reef in Australia. Along with the places of extraordinary beauty and natural wonder that are worthy of protection, the UNESCO World Heritage list also includes those areas that tell us about the evolution of life on the Earth, such as Wadi al-Hitan (valley of whales) in Egypt, where many fossilized skeletons of whales were found.

 

Everyone wants to go on a holiday to scenic places. As a result, more and more hotels, roads, and airfields are built in and around tourist spots. A huge amount of water is required in the hotels to provide hygiene and catering services to tourists. A lot of waste water and garbage are also produced in the process. Tourists often litter the places they visit with polythene and leftover food without thinking about the damage they are causing to the environment.

Overfishing means the practice of catching fish faster than they can reproduce through natural processes. Overfishing inevitably leads to the depletion of other marine species including birds and mammals. As a result, the food chain gets disturbed and animals and plants start reproducing in an uncontrolled way. The natural equilibrium between the living communities in a marine ecosystem gets disturbed - and this is a serious environmental catastrophe. 

In a greenhouse, the air gets heated up because the warm rays of the sun get trapped by the roof and the walls and are not reflected outwards completely. This situation is comparable to the conditions currently prevailing on the Earth. The layer of the atmosphere, which acts like the glass roof, contains greenhouse gases, such as water vapour, carbon dioxide, methane, nitrous oxide, and ozone, in appropriate amounts to keep the Earth comfortably warm. Due to irresponsible human activities, the carbon dioxide content has increased by 20% and methane content by 90%. As a result more heat is getting trapped and making the Earth warmer than usual. The increased temperature is causing the ice of the polar caps and glaciers to melt; this has led to a rise in sea levels and drastic climate changes all over the world. 

Symbiosis is a phenomenon in which two living organisms live together in such a way that they are mutually beneficial to each other. For example, the colourful clownfish live in a symbiotic relationship with the sea anemones. The clownfish enjoy the protection of the poisonous nettle fibres of the sea anemone and the sea anemone survives on the left-over food of the fish. The lichens that live in association with a fungus and an alga are also good examples of symbiotic relationships. Through the close interaction between its symbiotic partners, the lichens are able to grow in places, where they could never have existed alone.

Plants reproduce in a variety of ways. Many species build side shoots, from which new plants grow. Plants like mosses and ferns reproduce with the help of spores, which are distributed by the wind and grow to become new plants. ‘Higher plants’ or the seed plants with male and female sexual organs have stamens with pollen and the stigma. The male pollen sticks to the stigma and is passed on to the egg cell in the ovary. A fertilized egg ripens to become a fruit, which contains the seeds. The seeds can be dispersed widely through wind or through animals who eat the fruits and discard the seeds.

 

Roots absorb water and the dissolved nutrient salts from the soil. They also store the nutrients as a reserve that the plant can survive on, when the soil dries up. The roots also anchor the plant firmly in the soil to safeguard against uprooting due to wind and bad weather. Roots change shape and adapt depending on their environment. Shallow-rooted plants, such as spruces, can hold their ground even at places where the soil cover is very thin. Plants such as pine trees, whose tap root grows deep in the ground, are found at places where water is available at great depths inside the earth.

When trees grow, they accumulate wooden fibres around their heartwood. These fibres are bright and porous in spring so that a lot of water can reach the fresh leaves through them. By autumn, they become darker and thicker so the tree becomes stable and resistant to frost in the winter rest period. This process forms a bright ring and a dark ring around the heartwood every year. If you count the dark rings of a horizontal cross section of the tree trunk, you can find out the age of the tree. In the tropics, where there are no distinct seasons, the trees do not develop any rings. They grow all round the year and do not have any rest period. 

Algae are plant-like living organisms. They live in the seas, freshwater or damp land areas. They range from tiny single-celled organisms, which can be seen only under a   microscope, to larger plant-like planktons, used as food by blue whales or flamingoes. Large, leaf-like algae, known as ‘seaweed’, grow extensively in shallow waters to form dense underwater forests.

Many lichens grow in inhospitable terrain; for instance, in the rocky highlands and cold Arctic. They also grow on the walls of the houses in big cities. The growth rate of lichens is very slow—a few species grow less than one millimetre in a year. If you step on them, you may destroy in seconds a plant that took hundreds of years to grow. Since lichens are very sensitive to air pollution, they are often used as pollution indicators. The cleaner the air the more lichen will grow. 

The main difference between trees and shrubs is their size. Trees are much taller than shrubs and their root balls (system of roots with attached soil that supports the health of the tree) are also bigger. Unlike the thin and flexible stalks or stems of the shrubs, trees have thick stems to bear the load of the heavier and bigger leaves, branches, and fruits. Since trees are taller, they need to transport water from the soil much further up than the shrubs. This is done by several thin hair-like pipes in the stem and the branches.

In nature, there are ‘producers’ that build the biological mass, and ‘consumers’ that eat. Producers are the plants, which grow and create energy with the help of photosynthesis. They are eaten by a consumer, and that consumer is often eaten by another consumer. This chain of consumers is called the ‘food chain’. A short food chain is grass – cow - man. A longer one is algae - water flea – herring – seal - polar bear: A water flea eats algae, a herring eats many water fleas, a seal eats herrings, and the polar bear eats the seal. Ultimately, a lot of algae are needed to feed a polar bear. When the polar bear dies, its meat is either eaten by other animals or it is decomposed into nutrients by bacteria. These nutrients are again used by the algae to create energy, and thus the food chain gets completed.

Camels can manage for about two weeks without drinking water because they can store up to 150 litres of water in their bodies. Fat is also stored in their humps and this store of energy can sustain them for about 30 days without food. Furthermore, unlike most other mammals, camels can change their body temperature. At night they lower their body temperature considerably so that during the day the body warms slowly and they do not sweat much. Consequently, there is no loss of fluids early in the day.