A tooth consists of three main parts, the crown, the root and the neck.

The crown is the part of tooth that shows above the gum.

The root is the part buried in the jawbone.

The point where the crown and the root meet is the neck of the tooth.

Testes, produces sperm and cells which produce male sex hormone,testosterone

Scrotum,contains the testes

Epididymis,temporarily stores sperms

Sperm duct(vas deferens), carries sperms from epididymis to penis during ejaculation

Prostate gland,secretes seminal fluid which contains the enzymes and nutrients to activate and nourish sperms. Fluid secretions combines with sperms from testes to form semen.

Water which does not lather readily with soap is called hard water

Hardness of water is caused by the presence of dissolved salts of calcium ion, magnesium ion or iron(III) ion in water

Water which lather readily with soap is called soft water.

Soft water does not contain calcium ion,magnesium ion or iron(III) ion

Advantages of hard water

* Has pleasant taste so used in brewery industry

* Hard water provides calcium, which is essential for bones, teeth, and shells formation in animals

* Hard water provides Ca²⁺ ions which help in blood clotting in animals

* Hard water provides Ca²⁺ ions which are used by plants to manufacture certain vital substances

* Reduces heart disease

Disadvantages of hard water

* It wastes soap

* It interferes with dyeing and tanning process.

* It tends to make white clothes grey when they are laundered.

Advantages of soft water

* Lathers well with soap, does not form scum therefore saves soap

* Suitable for dyeing and tanning

* Does not form scale in boilers, kettles, radiators etc.

Disadvantages of soft water

* Has unpleasant taste

* Lack of Ca²⁺ ions causes weak teeth and bones and does not promote good growth in shellfish, crabs and snails

* Increase the chance of heart disease

Work done (W) = Force(F) x Distance(D), W = F x D

Since the distance is what is being calculated for, make the distance the subject

Dividing both sides of the equation by force,

Work done / Force = Distance

⇒ Distance = Work done / Force

Work done = 60 and Force = 20

⇒ Distance = 60/20 = 3.0 m

Respiration

The chemical breakdown of organic food substances such as glucose in the living cells to release energy with or without molecular oxygen.

Burning

Combustion, or burning,is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.

Decomposition

The process or effect of simplifying a single chemical entity into two or more fragments.

Photosynthesis

Photosynthesis is the process by which green plants manufacture food (starch/glucose) using carbon dioxide and water in the presence of sunlight and chlorophyll.

Compound

A compound is a substance which contains two or more elements chemically combined.

Element

An element is a pure substance made up of atoms of the same kind

Mixture

A mixture is formed when two or more substances are combined physically.

Ion

Any atom or group of atoms that bears one or more positive or negative electrical charges.

Positively charged ions are called cations and negatively charged ions, anions.

Cation is a positively charged atom or group of atoms and formed when an atom or group of atoms lose electrons.

Anion is a negatively charged atom or group of atoms and formed when an atom or group of atoms gain electrons.

How Shadows Are Formed

An opaque object blocks the light falling on it. This creates an area of darkness on the side of the object away from the source of light.

A translucent object also creates a faint area of darkness.

An area of darkness formed by an opaque object obstructing light is called a shadow.

The following three things are required for a shadow to form:
1. a source of light
2. an opaque object
3. a screen or surface behind the object.

Malnutrition

Malnutrition is a condition that occurs when one is not obtaining enough nutrients.

A condition which occurs when there is a deficiency of certain vital nutrients in a person's diet

Some deficiency diseases and their causes

When writing the chemical formula, the element(s) or compound(s) exchange their valencies.The sulphur has that of the aluminium element's valency (3) and so the value of y will also be the valency for sulphur

The atomic number for sulphur is 16 so on the electronic configuration, sulphur will have 2,8 and 6 on the last shell.

In order for sulphur to attain stability, it has to gain 2 electrons to make it 8 in the last shell, hence the valency of sulphur is 2 and so the value of y will be 2 (the valency of sulphur)

NOTE: The atomic number for aluminium is also 13, hence the electronic configuration will be 2,8 and 3. Aluminium could lose its 3 electrons in order to be stable, hence the valency of aluminium is also 3

Hence the chemical formula for aluminium sulphide is Al₂S₃

Renewable Energy

Renewable energy is defined as energy that is produced by natural resources—such as sunlight, wind, rain, waves, tides, and geothermal heat—that are naturally replenished within a time span of a few years.

A renewable energy source means energy that is sustainable - something that can't run out, or is endless, like the sun.

Sources of Renewable Energy

1. Solar energy
2. Wind energy
3. Hydro energy
4. Tidal energy
5. Geothermal energy
6. Biomass energy

Clay has the smallest particle size of any soil type, with individual particles being so small that they can only be viewed by an electron microscope due to that, they have slow permeability resulting in a very large water-holding capacity. Because the soil particles are small and close together, it takes water much longer to move through clay soil than it does with other soil types. Clay particles then absorb this water, expanding as they do so and further slowing the flow of water through the soil.

A legume is a plant in the family Fabaceae.Legumes produce a botanically unique type of fruit – a simple dry fruit that develops from a simple carpel and usually dehisces (opens along a seam) on two sides.They are characterized by having a legume-type of fruit (or pod) and compound, stipulate leaves. Examples are groundnut, Beans,Peanuts Peas, Soybeans, Alfalfa, Clover, Carob,Chickpeas, Lentils, Lupins Mesquite, Tamarind, Mimosa.

By magnetization we can separate sulfur and iron fillings. Take a magnet near to the mixture it will attract iron fillings and the remaining thing will be sulfur.

Color is an important physical property of soils that allows us to know some of its most important characteristics, such as mineral composition, age and soil processes, chemical alteration, carbon accumulation, the presence of hurrified organic matter. The soil may be black, red, yellow or coppered colored. From the color of the soil, we get an ideal of the fertility, drainage and other such properties.

The digestion of certain fats begins in the mouth, where lingual lipase breaks down short chain lipids into diglycerides. The presence of fat in the small intestine produces hormones that stimulate the release of pancreatic lipase from the pancreas, and bile from the liver, to enable the breakdown of fats into fatty acids. The complete digestion of one molecule of fat (a triglyceride) results in three fatty acid molecules and one glycerol molecule.

Unit of potential difference is joule per coulomb, given the name volt (V) after Alessandro Volta. The familiar term voltage is the common name for electric potential difference. Keep in mind that whenever a voltage is quoted, it is understood to be the potential between two points.

Mass = 40 g
Volume = 20 cm³

Density = $\frac{\mathrm{40\; g}}{\mathrm{20 }{\mathrm{cm}}^3}$

Density = 2 g cm^-3

Nutrients that plants require in larger amounts are called macronutrients. About half of the essential elements are considered macronutrients: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur.

Excretion involves the separation and elimination of metabolic waste products from the body. Various organs are involved in this process: the lungs, gills, skin, etc. The kidneys and their ducts are the major full-time excretory organs and comprise the excretory system.

pollen is produced by the anthers of the stamens in flowers. In gymnosperms, it is formed in the microsporophylls of the microstrobili (male pollen cones). Pollen consists of one or more vegetative cells and a reproductive cell. A pollen grain itself is not the male gamete. In angiosperms or the pollen containers (anthers) burst open in an explosive fashion when the sun hits them, scattering the pollen widely into the air. The stigmas often are long and divided into arms or lobes, so that a large area is available for catching pollen grains. Moreover, in open areas

The pressure in a liquid is different at different depths. Pressure increases as the depth increases. The pressure in a liquid is due to the weight of the column of water above. Since the particles in a liquid are tightly packed, this pressure acts in all directions. For example, the pressure acting on a dam at the bottom of a reservoir is greater than the pressure acting near the top. This is why dam walls are usually wedge-shaped. The greater pressure at the bottom would give a greater ‘force per unit area’ on the wall.

The World Health Organization (WHO) defines an adolescent as any person between ages 10 and 19.

Radiation is the process in which heat is transmitted one place to other directly without intervening medium. We get radiation of sun without an intervening medium

Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality. Soil factors: Soil moisture, color, soil air, soil temperature, soil mineral matter, inorganic and organic components, microorganisms, soil reaction

Holes and electrons are the two types of charge carriers responsible for current in semiconductor materials. A hole is the absence of an electron in a particular place in an atom. In P-type semiconductor material, holes are the majority carriers and electrons are the minority carriers while in N-type semiconductor material, electrons are the majority carriers and holes are the minority carriers

The dry season is the period where there is very little or no rainfall. In the southern part of Ghana, the dry season occurs between November to February. The period is much longer in the Northern part which occurs between November to June.

One of the problems with clay soil is its slow permeability resulting in a very large water-holding capacity. Because the soil particles are small and close together, it takes water much longer to move through clay soil than it does with other soil types. Clay particles then absorb this water, expanding as they do so and further slowing the flow of water through the soil. This not only prevents water from penetrating deep into the soil but can also damage plant roots as the soil particles expand.

• Alley cropping is a specific practice in which trees or shrubs and agricultural crops are grown in alternate rows The trees are commonly pruned to limit the shading of the agricultural crop. Alley cropping can also contribute to nutrient cycling and erosion control.
• Bush burning is the removal of the natural vegetation cover that protects the soil surface through the use of fire. This exposes the land to the effect of wind, soil erosion ,water erosion and ultraviolet radiation.
• Overgrazing is grazing by livestock or wildlife to the point where the grass cover is depleted, leaving bare, unprotected patches of soil. As a result, water and wind cause erosion, especially on clay soils, and the growth of poisonous plants and thorny shrubs may increase.

Therefore Bush burning and Overgrazing promote soil erosion.

A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light.

A semi-metal is a material with a very small overlap between the bottom of the conduction band and the top of the valence band. According to electronic band theory, solids can be classified as insulators, semiconductors, semimetals, or metals. The semimetals or metalloids are listed as boron, silicon, germanium, arsenic, antimony, tellurium, and polonium.

The periodic table is the arrangement of element in order of atomic number, usually in rows, so that elements with similar atomic structure (and hence similar chemical properties) appear in vertical columns.

A fluid is matter that flows when a force is applied to it. All gases and all liquids are fluids.

Fractional distillation or distillation is a method for separating a liquid from a mixture of two or more liquids. For example, liquid ethanol can be separated from a mixture of ethanol and water by fractional distillation.

When Hydrochloric acid react with magnesium a gas is always liberated.

An acid is a substance that donates protons (in the Brønsted-Lowry definition) or accepts a pair of valence electrons to form a bond (in the Lewis definition). acid, any substance that in water solution tastes sour, changes the color of certain indicators (e.g., reddens blue litmus paper), reacts with some metals (e.g., iron) to liberate hydrogen, reacts with bases to form salts, They react with the calcium carbonate to give a gas and promotes certain chemical reactions (acid catalysis).

Fish gills are organs that allow fish to breathe underwater. Most fish exchange gases like oxygen and carbon dioxide using gills that are protected under gill covers on both sides of the pharynx. Gills are tissues that are like short threads, protein structures called filaments

The slightest gust of wind catches the elaborate crown of plumose hairs, raising and propelling the seed into the air like a parachute. The pappus is persistent ant and hence found attached to even small, single seeded fruits. It acts like a parachute that allows the wind carry them to great distances.