My Science School

Land on the Earth

The earth is a huge ball, but it is not smooth all over like a ball that you bounce or roll. The earth’s surface is full of bumps and dips, but some parts of it are smooth. Where there’s no water, there is land.

Some of the earth’s surface is on the ocean floor. You live on one of the earth’s continents - or maybe on an island. You may live on a mountain, in a valley, on a plain, or in a desert.

Land is the solid surface of the Earth that is not permanently covered by water. The vast majority of human activity throughout history has occurred in land areas that support agriculture, habitat, and various natural resources. Some life forms, including terrestrial plants and terrestrial animals, have developed from predecessor species that originated in bodies of water.

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The glowing sun glares down on a vast sea of sand. As far as the eye can see, sand stretches in great brown ripples. The air is so hot it seems to shimmer as it rises from the sand. Not even the tiniest green plant is in sight.

Most people picture this endless, hot sandy land when they think of a desert. But there are many kinds of deserts. Some deserts are sandy places with very few plants. Others are flat plains with many kinds of plants. Some deserts are bare spots near seashore, while others are rocky areas high in the mountains. Some deserts are hot all year round. Others are hot or warm only in summer.

But one thing that is true of all deserts is that they are places where little rain falls. It does rain in deserts, but usually not much. Some parts of deserts get just a sprinkle every few years. Sometimes a desert is so hot that the rain dries up before it reaches the ground! In some deserts, heavy rain can cause sudden floods because the earth can’t soak up water fast enough.

Scientists say that some deserts were once green and fertile. Changes in climate made the rains stop and turned the land to desert.

The dry wind whispers as it passes over high, rocky deserts. Here there is little change. The rocks look the same year after year. But in a sandy desert, you might have a hard time finding the same spot from one year to the next. Hills of sand, called dunes, shift and change shape.

There are two kinds of dunes in the desert. One is usually crescent-shaped. A crescent is like a half circle. This dune builds up gradually into a long slope on the side from which the wind comes. It then drops steeply on the other side.

The second type of dune takes shape along the same direction that the wind blows. It has long, wavy ridges with the same kind of slopes on both sides.

Winds shift the sand from one shape to another. As desert sands shift, the dunes move. As the dunes move, they can cause a lot of damage to any buildings in their path. Desert towns sometimes disappear under shifting sand.

Maybe you have used oil on your bicycle chain to keep it from squeaking. Did you know that oil was once part of the earth? It starts as a thick dark liquid called crude oil that is found between layers of rock deep inside the earth’s crust. Crude oil is also called petroleum.

Crude oil is a fossil fuel. This means that it started forming millions of years ago from dead plants and animals that had lived in the ocean. Over millions of years, these dead plants and animals piled up on the ocean floor. Thick layers of sand and soil covered them. The sand and soil squeezed together under their own weight and the weight of the water pressing down on them. They were pressed so hard that they turned into rock. Scientists believe that the weight of the rock helped turn the piles of dead plants and animals into oil.

People today use oil for many things. They use oil to heat homes and to run cars, planes, trains, ships, and trucks. They also use oil to make such things as medicines and plastics.

Oil companies get oil by drilling into the earth’s crust. They pump out the oil that is trapped under the earth’s surface. They even pump oil from under the ocean floor.

Because of its many uses, oil has become very valuable. But it takes millions of years for the earth to make more oil, so we need to make sure we don’t waste it.

Imagine a giant dinosaur moving along a lakeshore 80 million years ago. It is searching for food. The dinosaur sees some plants and wades out to them. But before it reaches the plants, it steps into a deep hole filled with soft, wet mud. The dinosaur sinks deeper and deeper into the mud, and the dinosaur drowns.

Over time, the soft parts of the animal’s body rot away. Only its bones are left, covered by mud. For many years, layers of sediment pile on top of the mud and pack it tightly around the bones. Eventually, the packed mud turns to clay. After many more years pass, the clay turns to rock.

During all this time, minerals in the water of the lake fill the hollow places in the bones. The minerals harden and the skeleton of the dinosaur is preserved. The bones in the rock are called fossils.

There are other ways for fossils to be made. And, fossils exist for many kinds of living things - from bugs to plants to woolly mammoths - not just for dinosaurs.

Monozygotic twins or identical twins share the same genetic make-up (or DNA) as they originate from a single zygote (fertilized egg). They are genetically ‘similar’, but not exactly the ‘same’. They may have same hair colour, similar eyes and similar nose, but may differ in other aspects. And fingerprints are definitely not identical among such twins because first, fingerprints are not an entirely genetic characteristic, and second, a variety of environmental factors influence one’s fingerprint patterns.

A person’s fingerprints are formed when he or she is a developing baby in the mother’s womb. The fine details on fingerprints are influenced by random stress experienced in the womb – the length of the umbilical cord, access to nutrition, blood pressure, rate of finger growth at the end of the first trimester, and the position in the womb. Identical twins, though developing from one zygote, occupy different positions in the womb and these variations are enough to make a difference.

 

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To fight climate change, countries and organisations around the world have launched ambitious tree planting initiatives. India has pledged to get 33% of its geographical area under forest cover by 2022, Compared to the existing 24%. The United Nations launched the Bonn Challenge to bring 150 million hectares of degraded and deforested land into restoration by 2020 and 350 million by 2030. More than 74 governments, private associations and companies have pledged over 210 million hectares to the Challenge.

Trees are essential to life on Earth. They provide a home to plants and animals, soak up carbon dioxide, and provide food, fuel and medicines. Scientists have claimed that planting billions of trees could remove two-thirds of all the carbon dioxide created by human activity. Although such tree-planting initiatives could take a hundred years to be fully effective in addressing climate change, along the way they would reduce the consequences of the climate crisis - protecting soil from erosion, reducing the risk of flooding and providing habitats for a vast range of animals and plant species.

Tree planting is, indeed, a brilliant solution to tackle climate change and protect biodiversity. But the idea should not be to fill every available space with trees. Species need to be chosen carefully to ensure they grow well. Planting the right trees in the right place is crucial, say scientists. Otherwise, the entire exercise could become futile.

Scientists have recently proposed 10 golden rules for tree-planting, in a study published in the journal Global Change Biology. They say must be a top priority for all nations this decade. They are:

Protect existing forest: Stopping deforestation and protecting existing trees should also be part of the plan. Intact, old forests are better at soaking up carbon due to their complex structure. The old large trees are more resilient to fire and drought.

Make local people integral to the project: For successful outcomes in both forest protection and reforestation, it is vital to include local communities from the planning stage through to delivery and monitoring.

Maximise biodiversity recovery to meet multiple goals: Reforestation is a means to achieving various goals, typically climate-change mitigation, biodiversity conservation, socio-economic benefits (including food security), soil and hydrological stability and other ecosystem services.

Select appropriate areas for reforestation: Avoid previously non-forested lands and connect or expand existing forest, rather than using other natural habitats such as grasslands or wetlands.

Use natural regeneration wherever possible: Natural regeneration can be cheaper and more effective than tree planting. Work towards low intervention, including protection from further damage such as grazing or fire, and rewilding, which includes the selective reintroduction of missing fauna to restore natural processes.

Select the right species to maximize biodiversity: Where tree planting is needed, picking the right trees is crucial. Scientists advise a mixture of tree species naturally found in the local area, but avoiding trees that might become invasive.

Use resilient plant material: To ensure the survival and resilience of a planted forest, it is vital to use material with appropriate levels of genetic diversity, consistent with local or regional genetic variation.

Plan ahead: From seed collection to tree planting, develop the required infrastructure, capacity and seed supply system well in advance.

Learn by doing: Planning decisions should be made by combining both scientific and indigenous knowledge. Ideally, small-scale trials should be implemented before large-scale tree planting commences, to test the effectiveness of proposed techniques.

Make it profitable: The sustainability of tree re-planting rests on a source of income for all stakeholders, including the poorest.

 

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Morning breath is often caused by the lack of saliva in your mouth. When you’re awake your mouth usually produces enough saliva to break down food particles that allow odor-causing bacteria to grow. But when you’re asleep, the saliva production slows down and the bacteria starts growing and produces what is called ‘volatile sulfur compounds’ or VSC which cause your mouth to stink.

You can reduce the effects of morning breath by practicing good oral hygiene, especially before bed. Brushing and flossing helps get rid of pockets of food that can harbor bacteria. You can also clean your tongue to remove large amounts of bacteria that have gathered to give you morning breath during the night.

To clean your tongue, you’ll need a tongue scraper, a toothbrush with soft bristles, or even a spoon. If your tongue is pink and shiny, it isn’t harboring much bacteria, but if it has a white film covering it, it’s a sign you have bad breath. If you need confirmation, lick your clean wrist and let your wrist dry. Then, smell it. If your breath is stinky, your wrist will be stinky too.

Get rid of the film by either gently scraping your tongue with the tongue scraper or the spoon. Or, alternatively, you can brush your tongue to get it clean. That way, you’ll have less of a chance of having morning breath when you wake up.

 

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Bad breath, also called halitosis, can be embarrassing and in some cases may even cause anxiety. It's no wonder that store shelves are overflowing with gum, mints, mouthwashes and other products designed to fight bad breath. But many of these products are only temporary measures because they don't address the cause of the problem.

Bad breath odors vary, depending on the source or the underlying cause. Some people worry too much about their breath even though they have little or no mouth odor, while others have bad breath and don't know it. Because it's difficult to assess how your own breath smells, ask a close friend or relative to confirm your bad-breath questions.

The best method to reduce halitosis is good oral hygiene. This ensures that cavities are avoided and reduces the likelihood of gum disease.

It is recommended that individuals visit the dentist for a check-up and cleaning twice a year.

The dentist may recommend a toothpaste that includes an antibacterial agent or an antibacterial mouthwash.

Alternatively, if gum disease is present, professional cleaning may be necessary to clear out the build-up of bacteria in pockets between the gums and teeth.

 

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Spiders can’t chew or swallow so how do you think they eat?  They can only eat liquid lunches!  To do this, they inject their prey with poison using their fangs.  The poison turns the insides of insect to a watery goop and the spider just sucks it up.  

Spiders are not miniature vampires; all species, as far as we know, digest some solid parts of their prey. What makes it especially interesting is that the digestion process begins outside the spider, where anyone who wants to look can see how it works.

Put a medium-sized insect in the web of a large orbweaving spider in the garden. You will see the spider bite the prey, wrap it in silk, wait for it to die, then begin to eat. As a first step in eating, the spider will literally vomit digestive fluid over the prey. Then the prey is chewed with the "jaws" (chelicerae), and the fluid is sucked back into the mouth together with some liquefied "meat" from the prey. The spider repeats this process as often as necessary to digest, and ingest, all but the inedible hard parts. What is discarded afterwards is a small ball of residue.

Spiders other than orbweavers may eat the prey's body but discard some of the wings, legs, etc. Spiders with very small (if strong) jaws (such as crab spiders and cobweb weavers) make small holes in the prey and vomit their digestive fluid into the prey's body, the end result being a hollow shell with some or most of the muscles and internal organs digested and sucked out.

 

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Technically speaking, spiders are not insects! Why aren’t they exactly? We’ll look into a few main reasons why spiders and insects are so different. But first, let’s break down what spiders and insects have in common, which is actually quite a bit.

To understand the similarities and differences between spiders and insects, we have to cover a bit of taxonomy. Taxonomy is the science of classifying all living things. Spiders, insects, fish, birds, and humans all fall into the Kingdom Animalia. Pretty much every animal is able to breathe and move, unlike plants and fungi. Additionally, animals are multicellular, unlike bacteria. Let’s dive deeper into the world of taxonomy and discover more about the classification of spiders and insects.

The next taxonomic level down is where spiders and insects lose their similarities. Spiders are in a class of animals known as arachnids. Spiders, scorpions, mites, and ticks are all different kinds of arachnids. Perhaps the biggest difference between arachnids and insects are the number of legs they have. One of the defining characteristics of spiders and other arachnids is that they have 8 legs. Insects, on the other hand, only have 6. This difference may not seem that significant, but it’s one of the most important things that separate these two classes of animals!

Next up is the number of body segments. Spiders have two segments – the abdomen, and the cephalothorax (which is a combination of a head and thorax). Insects boast three distinct segments – an abdomen, a thorax, and a head. Although they serve essentially the same functions, the body segments are another characteristic that spiders and insects do not have in common.

 

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People with the disorder pica compulsively eat items that have no nutritional value. A person with pica might eat relatively harmless items, such as ice. Or they might eat potentially dangerous items, likes flakes of dried paint or pieces of metal.

In the latter case, the disorder can lead to serious consequences, such as lead poisoning.

This disorder occurs most often in children and pregnant women. It’s usually temporary. See your doctor right away if you or your child can’t help but eat nonfood items. Treatment can help you avoid potentially serious side effects.

Pica also occurs in people who have intellectual disabilities. It’s often more severe and long-lasting in people with severe developmental disabilities.

There’s no single cause of pica. In some cases, a deficiency in iron, zinc, or another nutrient may be associated with pica. For example, anemia, usually from iron deficiency, may be the underlying cause of pica in pregnant women.

Your unusual cravings may be a sign that your body is trying to replenish low nutrient levels.

People with certain mental health conditions, such as schizophrenia and obsessive-compulsive disorder (OCD), may develop pica as a coping mechanism.

 

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Emotional eating is the tendency of its sufferers to respond to stressful, difficult feelings by eating, even when not experiencing physical hunger. Emotional eating or emotional hunger is often a craving for high-calorie or high-carbohydrate foods that have minimal nutritional value. The foods that emotional eaters crave are often referred to as comfort foods, like ice cream, cookies, chocolate, chips, French fries, and pizza. About 40% of people tend to eat more when stressed, while about 40% eat less and 20% experience no change in the amount of food they eat when exposed to stress.

Warning signs for emotional eating include a tendency to feel hunger intensely and all of a sudden, rather than gradually as occurs with a true physical need to eat that is caused by an empty stomach. Emotional eaters tend to crave junk foods rather than seeking to eat balanced meals, and the urge to eat is usually preceded by stress or an uncomfortable emotion of some kind, like boredom, sadness, anger, guilt, or frustration. Other hallmarks of emotional eating are that the sufferer may feel a lack of control while eating and often feels guilty for what they have eaten.

A number of different health care professionals evaluate and treat emotional eating and may also help with weight loss when this contributes to overweight or obesity. As this symptom can occur at nearly anytime across the life span, everyone from pediatricians, family practitioners, and other primary care physicians may address this problem. Nurses, nurse practitioners, and physician assistants may be involved in caring for emotional-eating sufferers. Mental health professionals who are often involved in assessing and treating this issue include psychiatrists, clinical psychologists, social workers, and licensed counselors. While any one of these practitioners may care for people who engage in emotional eating, more than one may work together to help the person overcome this symptom.

 

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Binge eating disorder (BED) is a type of feeding and eating disorder that’s now recognized as an official diagnosis. It affects almost 2% of people worldwide and can cause additional health issues linked to diet, such as high cholesterol levels and diabetes.

BED was first explained in 1959 by Albert Stunkard, a psychiatrist, and researcher, as Night Eating Syndrome (NES). The term Binge Eating Disorder was created to define similar binge eating behavior without the nocturnal aspect.

Though BED can occur in men and women of normal weight, it often leads to the development of unwanted weight gain or obesity, which can indirectly reinforce further compulsive eating.

Men and women suffering from BED struggle with emotions of disgust and guilt and often have a related co-morbidity, such as depression or anxiety.

Professional support and treatment from health professionals specializing in the treatment of binge eating disorders, including psychiatrists, nutritionists, and therapists, can be the most effective way to address BED.

Such a treatment program would address the underlying issues associated with destructive eating habits, focusing on the central cause of the problem.

It is necessary to concentrate on healing from the emotional triggers that may be causing binge eating, having proper guidance in establishing healthier coping mechanisms to deal with stress, depression, anxiety, etc.

 

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Anorexia nervosa is a serious mental health condition and a potentially life threatening eating disorder. However, with the right treatment, recovery is possible.

The exact cause of anorexia is not known, but research suggests that a combination of certain personality traits, emotions, and thinking patterns, as well as biological and environmental factors might be responsible.

People with anorexia often use food and eating as a way to gain a sense of control when other areas of their lives are very stressful or when they feel overwhelmed. Feelings of inadequacy, low self-esteem, anxiety, anger, or loneliness also might contribute to the development of the disorder. In addition, people with eating disorders might have troubled relationships, or have a history of being teased about their size or weight. Pressure from peers and a society that equates thinness and physical appearance with beauty also can have an impact on the development of anorexia.

Eating disorders also might have physical causes. Changes in hormones that control how the body and mind maintain mood, appetite, thinking, and memory might foster eating disorders. The fact that anorexia nervosa tends to run in families also suggests that a susceptibility to the disorder might partially be hereditary.

 

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People Who Work with Animals

Do you love animals? There are many kinds of jobs for people who do. A few of those jobs are listed here.

Veterinary surgeons, or vets, keep animals healthy. City vets deal mostly with pets, giving them injections to keep them well. Country vets take care of farm animals, such as cows and horses.

Zoologists study animals to find out where and how they live, how they get along with people and other animals, and how they change over time. Zoologists work in laboratories, zoos, or museums. Or they work at wildlife refuges in the jungle, at sea, or wherever animals live.

Naturalists study nature by watching it carefully. They hike in the country to watch birds, or they visit museums, parks, and zoos. Many naturalists keep notes, sketches, and photographs of everything they see. You don’t have to wait to be a grown-up to be a naturalist! Many areas have nature-study programmes for children.

Game wardens and rangers help protect wild animals in National parks and game preserves. They rescue animals stranded by floods or fire and make sure people obey fishing, hunting, and camping laws.

Farmers and ranchers raise livestock that provide food for people all over the world. Farmers raise such livestock as chickens, pigs, and dairy and beef cattle. Ranchers raise sheep and cattle on huge farms.

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