Definitions for Kids


Vacuole is a physical component of plant and animal cells. It is one of those few cellular properties that are found in both plants and animals. However, the vacuoles found in plants are much larger than those found in animals.

What is a Vacuole?

A vacuole is a small sac like structure in plant cells that stores food or nutrients, water and also waste. Imagine a backpack with all your essential nutrients and water. You may also imagine a microscopic bin that contains all the waste material generated by a plant or animal cell which would then be got rid of.

Purpose of Vacuoles

The purpose of vacuoles is pretty straightforward. It stores water for the cell. As and when needed, it releases the water to be used by the plant, either for photosynthesis or any other circulatory need. Vacuoles also store the food for the plants. It releases the nutrients as and when necessary for the cell. Every cell has a vacuole. The same vacuole also stores the waste materials generated so the entire cell doesn’t get contaminated by the toxins or get affected in any way by the undesirable waste material which must be got rid of. A vacuole may also break down the waste into smaller bits so it is easier to get rid of. Smaller bits of waste matter or toxins pose a much reduced threat to the health, structure and integrity of the plant cell.

Significance of Vacuoles

A vacuole can be considered as a treasure trove for plant cells or a detoxifying chamber when waste material is stored. Vacuoles are not only responsible for the supply of nutrition to the plant cells and getting rid of toxins but they also contribute to the physical structure or form of the plant cell. Every plant cell has a membrane or wall that contains various components. Every component lends to the structural form and integrity of the cell. While the cell wall protects the overall structure or shape, it is the components that are responsible for the overall well being and retaining of the structure.

When a vacuole is healthy and filled with water or nutrients, it will ensure that the plant cell has its optimum form and integrity. If vacuoles start to shrink because of lack of water or nutrients then the size and shape of the plant cell will also shrink. When you see a drooping plant, it could be due to a shrunk vacuole. The cells will be capable of retaining their original size and form if the vacuoles get filled up again with water, nutrients and then waste.


The constitution of the United States bestows certain rights on the federal government and every state government. Both the federal and state governments can make laws. While the laws made by a state will be binding on the territory under its jurisdiction, federal laws are binding on all states, unless there is a state law that directly contradicts the federal law. It is in those contradicting laws where the supremacy clause comes in.

What is the Supremacy Clause?

The Supremacy Clause is laid out in the second paragraph of Article VI of the constitution. The clause essentially gives federal laws the upper hand over state laws when the two are in direct conflict or contradictory in nature. In other words, the federal laws will have jurisdictional authority over state laws in any and every case under judicial purview where the two laws are pitted against each other.

Unlike the many revisions, amendments and new laws that have been made over more than two centuries, the Supremacy Clause has been etched in the constitution since its first draft. The Supremacy Clause has been hotly debated by many. There are many proponents as well as critics of the law and in most cases subjectivity tends to dominate the viewpoints rather than objectivity. Over the years, the Supremacy Clause has been weirdly used by many judges. Like any other law, the Supremacy Clause is also under the subjective or objective interpretation of the presiding judge. Should the Supremacy Clause be exercised, the judge may avoid a conflict and may do away with the need of an appeal but that may not lead to the correct assessment. If a judge doesn’t exercise the clause then it leaves the case open for appeal at a higher court, in which case a federal judge is likely to enforce the clause.

Throughout history, Supremacy Clause has often been turned down or not exercised when the judges felt that the states need a more dominant control of its laws. During the civil war and many years later, the Supremacy Clause has been very rarely used. But since the early 1900s, especially after the 1930s, the Supremacy Clause has almost always been exercised and no judge at any level of appeal or court has tried to undermine it.

The Strengths & Pitfalls of the Supremacy Clause

The United States constitution is very lucid in many aspects. It allows every state to have its own laws. There are federal laws, some of which are binding on every state and some that are rather discretionary for the states. When any crime or legal issue crisscrosses more than two or three states, the federal laws come into effect. There is really no room for tussle. In some cases, jurisdictional issues do bear a hindrance but that has been changing over the years. Today, the civil law enforcement, the lawyers and the judges work with much more efficiency and coherence. However, the Supremacy Clause does raise a few questions, rather eyebrows when some crucial laws come into conflict.

There are some states that have legalized same sex marriage, some states have legalized marijuana, some states have lenient punishments for relatively heinous crimes and some states are opposing the minimum terms. Capital punishment and many laws are always on the table for debate among states and between most states and the centre or federal government.

The federal laws are always stronger than state laws. Being a federal law, it will always have more severe implications. But the fact that states have the liberty to make their own laws gets questioned when a state law is struck down to favor a federal law or its statute. If a state law is flawed, if it is not making appropriate sense in a given crime or if there is an associated federal or multistate context of the crime, then the Supremacy Clause make perfect sense.

The proponents of the Supremacy Clause argue that it is indeed necessary to empower the federal government to cut beyond the interstate relations or state laws that are more concise in their execution. Supremacy Clause tends to bring in a sense of balance. A country needs to have one set of laws. The states have the power to make laws but no law can overrule the federal law. In any scenario where the state law tries to supersede the federal law, it defeats the purpose of having one binding constitution and one set of laws. In that sense and from such a perspective, the Supremacy Clause is not only necessary but also important in striking the right balance. The Supreme Court can review the laws made by the Congress and strike them down if necessary. State laws are also subject to such reviews and the Supremacy Clause is needed to not allow complete authority of the state in contentious issues.


Literally, sectionalism is a preference of the political class or those in various echelons of power towards a particular region, religion, race or certain people. It is a tendency of focusing more on the interests of a certain group and not all citizens as a collective whole. The exaggerated or more than necessary devotion, interest and deeds favoring a particular state, city or town, religion or culture, ethnicity or just people hailing from a certain class, background or parentage is sectionalism.

Sectionalism: Illustrated!

There are federal laws and state laws. The laws of one state may vary from the laws of another state but the federal laws stand applicable as they are, equally for all states. There cannot be one federal law for a few states and another for other states. If that happens, then it would constitute to be sectionalism. The federal government cannot say that a certain financial crime in New York City is acceptable or not punishable with a jail term and the same crime committed in San Jose will be treated with a jail term. The law must apply equally for any and sundry.

Sectionalism stems from the personal preference of politicians and socioeconomic compulsions. It can also stem from political and religious considerations. Throughout history, politicians have tried to appease people. They try to cater to their own people, which traditionally has been people of the same race, in the same region, having born and brought up in the same place, having a certain social and cultural upbringing, hailing from a certain financial background and having specific interests or preferences that match those of the politician.

Appeasement almost always leads to sectionalism. Also, unequal laws or any practice that is not made a standard will create turmoil in some sections of the society which will also lead to sectionalism.

Sectionalism in History

There are many historians who believe that one of the causes of the civil war was sectionalism. Some states were willing to abolish slavery, accept new trade policies and rights. Some states were not willing to accept them. This led to a conflict which snowballed into the civil war. Of course there were other reasons but there are credible historians and authors who stress that sectionalism was one of the major causes of civil war. Across the world, sectionalism is practiced in many ways. Appeasing immigrants and treating them very stringently or almost racially are both variants of sectionalism.


Energy is usually classified into two types: static and kinetic. Gravitational, chemical, nuclear and elastic energy are examples of static energy. Heat, sound and electricity are examples of kinetic energy. Another type of energy that gets classified as kinetic energy is radiant energy.

What is Radiant Energy?

Any type of energy that can be transmitted through electromagnetic radiation is radiant energy. The exact transmission could be purely electrical or purely magnetic. In case the energy gets transmitted in both forms, as electrical and magnetic radiation, then it is referred to as electromagnetic radiation or radiant energy.

Light is Radiant Energy

The most commonly cited example of radiant energy is light. That is partly because light is a visible energy. We can either see energy or feel it. In many cases, we don’t see or feel the energy but only get to measure it using special instruments. Light is also the most prevalent radiant energy because it is not just light but a sum of many forms of energy.

Examples of Radiant Energy

All electromagnetic radiations are radiant energy. That includes x-rays, microwaves, radio waves, ultraviolet waves and visible light. Radiant energy doesn’t require any medium and can be transmitted regardless of the medium. In other words, radiant energy can travel or be transmitted through space which is essentially vacuum, air or atmosphere, solid objects including humans and nonliving matter in the world as well as different atmospheric conditions as found around other planets.

Transmission of Radiant Energy

Radiant energy is transmitted in the form of waves. Light energy, different parts of the invisible spectrum of light including every wavelength and frequency from gamma ray to long wave, gravitational waves and even celestial heat are transmitted as radiant energy. The waves have specific frequencies and wavelengths depending on the energy of the photons or particles of the energy. The type of energy that has longer wavelengths would have less active particles and those that have shorter wavelengths will have hyperactive photos or particles.

Radiant energy is transmitted primarily because of the motion of these photons, also known as charges. Their disturbance or motion causes a wave in space or any medium where it is generated or exists. These waves then lead to the transmission of the radiant energy. Like any other form of energy, radiant energy can also be converted and utilized in myriad ways. Radio, television, solar cells and cell phones are some of the devices that use radiant energy.


Preposition is a word that links a noun or pronoun to the other part of a sentence. It can also link a noun phrase, subject or object and general words that need to be connected to form a sentence. Prepositions are integral to sentence construction and hence pivotal to understand grammar.

What is Prepositional Phrase?

The term ‘prepositional phrase’ should be easy to understand. It is a phrase or a collection of words. Preposition is just one word. When two words or more serve the function of a preposition, those words are collectively called a prepositional phrase.

Prepositional phrases may contain two or more words and at least one preposition. It is unlikely that two prepositions may be needed but it is not rare. It must be noted that a prepositional phrase should not contain a verb and there should be no subject. There will be an object, there can be an adjective or the prepositional phrase itself can be the adverb or adjective.

The simple purpose of a prepositional phrase is to establish a literal sense and form a connection between the noun or pronoun with the rest of the sentence. A prepositional phrase becomes more important when it doubles up as an adjective or adverb, thus making the sentence more interesting.

Examples of Prepositional Phrase

• Take this simple sentence for instance: “This tiara with glitters is yours.”
• Now consider this sentence: “This tiara with golden glitters is yours.”

In the first case, ‘with glitters’ is the prepositional phrase. In the second case, ‘with golden glitters’ is the prepositional phrase. The second scenario is just more interesting although the message being conveyed is not very different and the sentence construction too remains the same. You would notice that the prepositional phrase doesn’t have any verb and it has no subject. It just is and makes sense on its own. Also, it makes complete sense when you read it in the larger context of the sentence.

There are more than a hundred prepositions in the English dictionary but the possibility of conceiving a prepositional phrase is much broader. That is primarily because of the words that you can insert in a prepositional phrase. For instance, you can come up with ‘down the stairs’, ‘up the hill’, ‘around the house’, ‘into the building’, ‘near the rigid door’, ‘within the pages’, ‘through the subway’, ‘in spite of’, ‘instead of’, ‘on account of’ and ‘because of’ among others.


The simplest definition of a line is it is the straight distance between two points. In geometry, line is a long thin mark made by a pencil or pen that runs straight from one point to another. In case the two points are fixed, it is called a line segment. If there are no apparent ends and the line seems to be infinitely long then it is known just as a line. If the line has one fixed end and stretches infinitely at the other end, then it is called a ray. A line has no thickness and is strictly a two dimensional figure.

What are Perpendicular Lines?

Perpendicular lines are a set of two lines that form a right angle or an angle of ninety degrees. Imagine a horizontal line, exactly flat, and no imagine a vertical line standing atop it. The horizontal and vertical lines would meet at a point and that would form two angles on either side. Both angles would be ninety degrees. These two lines are called perpendicular lines. These right angles are also known as perpendicular angles.

In case of perpendicular lines, one line could be finite and another could be infinite, one could be a ray and another could be a line segment and both could be lines with infinite lengths. The two perpendicular lines may meet at a particular point thus forming two right angles or the two lines may crisscross each other and continue on their path, thus forming four right angles. It is not necessary for perpendicular lines to be exactly horizontal and vertical as a pair. They can form any kind of shape or be tilted or angled in any way. Regardless of what kind of tilt they have, the resulting angles formed by the crisscrossing of the two perpendicular lines would also be ninety degrees.

Perpendicular Lines and Geometric Figures

Perpendicular lines don’t form any geometric figure or shape as such but when several perpendicular lines are brought together in specific ways, they can form square, cube, rectangle and the right triangle. Regular polygons usually don’t have perpendicular lines but irregular polygons can always have perpendicular lines forming one or more right angles. It all depends on the exact shape of the polygon, the number of sides and the length of the sides. Those would influence the angle and hence the likelihood of perpendicular lines forming a part of the geometric structure.


Our world has been around for billions and billions of years, and way back in the past, giant creatures called dinosaurs ruled the Earth. These dinosaurs are now more or less extinct, while others have managed to change and evolve in order to adapt to the world today, which is why we still have animals in our environment.

If dinosaurs no longer exist, how did we find out that they did exist in the past? The answer is easy. All over the Earth, millions of dinosaur fossils – which are naturally preserved remains – are being found and studied by a special kind of scientist called paleontologists. These professional dinosaur bone diggers are the reason why we know so much about prehistoric ages, thanks to their efforts to uncover the mysteries of the past.

1. Bones Aren’t All They Study

You would be surprised just how many clues dinosaurs left for us to find. Our modern paleontologists don’t only use bones to figure out the what’s, why’s, and how’s of the past – they can even use footprints, teeth, eggs, nests, and yes – even dung! While bones can be very helpful to figure out what a dinosaur may have looked like, these other clues can help us determine what they ate, where they liked to live, their migration patterns, and even their unique animal behaviors.

2. Fossil Means “Dug Up”

The word fossil is taken from the Latin word fossilis, which literally translates to “dug up.” This is because the fossils that our paleontoligsts are able to excavate are usually taken from sedimentary rock layers where they’ve been preserved through the years. Wondering how they got there? Good question! When a dinosaur dies, its body more or less stays in place. As the earth changes and as soil, mud, and other debris are layered over it, it slowly gets buried under the dirt. Because its death happened millions of years ago, you can just image how much earth has been piled up on top of its body! This is why paleontologists need to dig in order to find fossil remains.

3. Other Kinds of Fossils

Now, fossilization isn’t the only way that fossils form. Petrification is another common way that prehistoric remains have been preserved. Usually, prehistoric wood is found petrified. The main difference between petrification and fossilization is that the former means that components of the original object were replaced by minerals and thus preserved, while the second means the original object was lost, but its shape, size, and structure were embedded into a stone.

4. The Father of Paleontology

Georges Cuvier was a French naturalist and zoologist which many people regard as the father of paleontology. While he wasn’t the first to discover fossil remains (as people way, way back in ancient times had already unearthed them), he was given the name the father of paleontology because he ultimately proved the theory of extinction which paved the way towards the establishment of comparative anatomy and paleontology as recognized branches of science.

5. The Biggest Fossil

On display at the American Museum of Natural History in New York is what people believe to be the biggest fossil ever found. The titanosaur measures 122 feet from its head all the way down to the tip of its tail. The replica of the gigantic creature was created based off of 84 real fossils that were found in Patagonia in 2014. This species of dinosaur has yet to be given an official name, but they are believed to have existed between 95 to 100 years in the past, and weigh about 70 tons.

6. The Smallest Fossil

Funny enough, this fossil wasn’t actually the fossil being studied when it was found. Palaontologists were working to learn more about a fossilized spider, and so took an x-ray scan of it.

The results were surprising, not because of the spider itself, but because of the creature that was on it. Tiny mite just 170 millionths of a meter long, was found fossilized on the spider under scrutiny. This has now been recognized as the smallest fossil ever discovered, and can only be seen with the aid of a magnifying device such as a microscope or scanner.

7. The Oldest Fossils

Way back when the Earth was still new, the creatures that lived on it were more like organisms and less like animals. These organisms were usually bacteria, and they were the ones that really started all of it. From these tiny organisms, larger animals began to evolve and believe it or not, some even suggest that we came from them as well! The oldest fossil ever discovered was that of a cyanobacteria in Archaen rocks excavated in western Australia. It is said to be at least 3.5 billion years old.


The constitution of United States is a living document. It is not a scripture etched in stone that doesn’t have any room for interpretation, amendment or improvement. The constitution is consistently interpreted by the judicial system. It is amended and improved by the legislature. It is also acted upon in adhere to the various laws by the executive. The constitution would cease to evolve if there weren’t enough provisions in it to make such evolution possible. One such provision is the necessary and proper clause.

What is the Necessary and Proper Clause?

Also known as the elastic clause, the Necessary and Proper Clause is laid out in Article 1, Section 8 of the constitution of United States. Literally, the clause grants the authority to Congress to create and enforce any law that is necessary and proper. That is of course subjective, circumstantial and given the need of the hour. Also, the necessity and whether or not a law is proper depend on a sensible assessment of the proposed legislation, law or reform.

The Congress is the lawmaking body. Barring the exclusive domains of the executive and the realms of the judiciary, the Congress can make laws that would lay out the right way of doing things. They can also make laws that would govern the executive and for the judiciary to uphold.

Implications of the Elastic Clause!

When the constitution was first drafted or even conceived, there was clearly a need to keep provisions that would pave the way for making new laws as and when they were necessary. Surely, the constitution dating back more than two centuries couldn’t have accounted for laws that would be significant or needed today. Even today, we don’t know what laws we would need for our country five decades from now. If the constitution doesn’t or didn’t have any provision for lawmakers to make new laws, then it would become a redundant document and not an embodiment of our democracy.

Anyone who thinks that the elastic clause can be misinterpreted or is needless fails to recognize its significance. All laws that have been made over the last two centuries, allowing the country to achieve the echelons that it has and ensuring that we continue to evolve have been partly because of the consistent evolution of our constitution. That wouldn’t happen if the federal government or the Congress doesn’t have the authority to make laws that are necessary and relevant.


The planet we call earth is made of three types of rocks. The rocks are classified according to the way they form. The three types are: sedimentary, igneous and metamorphic rocks.

Sedimentary and Igneous Rocks

Sedimentary rocks are formed through the gradual deposition and accumulation of various materials, which could include organic and inorganic matter over a substantial period of time. They are so called because of the sediments that are deposited which eventually develop into a rock. Sedimentary rocks are of three types: clastic, chemical and organic. Igneous rocks are made of magma, either on the surface of the earth or inside the crust. Igneous rocks are of two types: intrusive and extrusive. Both sedimentary and igneous rocks are the primary types of rock formation. Metamorphic rock is not a primary rock.

What is Metamorphic Rock?

As the name implies, metamorphic rock is formed after a process of metamorphosis or metamorphism, in other words transformation. The metamorphosis or transformation in existing rocks can be brought about by the changes in atmospheric conditions or the immediate environment that includes heat and pressure.

It must be noted that metamorphic rocks are formed from existing rocks. They are not the first stage of any rock. Sedimentary and igneous rocks can become metamorphic rocks subjected to heat and pressure over time. When any rock is subjected to more heat and pressure than it can bear, there will be changes in its form or structure, chemical composition, texture and various properties. The rock may break down, it may become a completely different rock due to the changes of its components and the physical or chemical characteristics will be transformed. While sedimentary and igneous rocks are generally the earlier phase of metamorphic rock, there are many metamorphic rocks that have formed from an older or existing metamorphic rock.

Types of Metamorphic Rock

There are two types of metamorphic rock: foliate and non-foliate. Foliate metamorphic rocks will have a banded or layered appearance. Examples are slate, gneiss, schist and phyllite. Non-foliate metamorphic rocks do not have any layered appearance. Examples are marble, hornfels, novaculite and quartzite.

Metamorphic rocks are usually formed as a result of two types of metamorphism: contact metamorphism and regional metamorphism. Contact metamorphism is a process in which the exact cause for metamorphism is in direct contact with the existing rock. Regional metamorphism doesn’t require direct contact. The causal factor or factors will have an indirect impact and cause the metamorphism.


Earth is comprised of four spheres. The four spheres are lithosphere, hydrosphere, atmosphere and biosphere. Many people use the term geosphere to describe lithosphere. That is wrong. Many people also say that every sphere is essentially a geosphere because it is an integral part of the world. Geosphere is essentially a different classification which is the subject of another discussion.

As the names imply, hydrosphere is the part of the world that is water. It includes all oceans, seas, rivers, lakes and groundwater. Atmosphere is of course air and includes all the levels, right from troposphere to exosphere. Biosphere is all living organisms in the world. It includes humans, all animals, fishes, birds, plants and also microorganisms. Lithosphere is the earth’s crust.
What is Lithosphere?

Earth is a rock. There’s solid rock on the surface, there’s molten rock inside the core and mantle. The land and rocks that form the crust of the earth, which is the topmost layer, is referred to as lithosphere. There are some who believe that all lands and rocks of the earth would be lithosphere. But that is incorrect. The rocks in the mantle or the molten core do not fall under lithosphere. The classification for all land and rocks on and inside the planet is geosphere.

Hence, the hills and mountains or the plateaus you see, the topsoil and the vast terrains of cultivable, arid and semi arid lands, the ocean floors or the riverbeds, the crust that holds the groundwater and all rocks found on the surface of the earth or at the crust are a part of lithosphere. The layer known as lithosphere does not include magma or lava.

Lithosphere is effectively the host of life, of course with help from hydrosphere and atmosphere. All of biosphere resides or thrives in lithosphere. It is lithosphere that supports farming or agriculture, forests, mining of various materials that we need and all our cities or modern infrastructure rests on this layer.

Lithosphere is the most stable of all parts of the world but it is not the most predictable. If you consider the fluctuations in the climate which is effectively the atmosphere, the consistent flow and movement of the rivers and the waves in oceans respectively, then you would find lithosphere to be the safest and the most habitable part of the world. But it is a tad unpredictable when you factor in the tectonic movements.