Where is skeletal muscle found?

One step of the scientific method is to analyze information or data collected from the experiment to conclude whether the hypothesis is supported.

Recall that these make up thescientific method,described below:

• Problem:The question created because of an observation.Example: Does the size of a plastic object affect how fast it naturally degrades in a lake?
• Research:Reliable information available about what is observed.Example: Learn how plastics are made and understand the properties of a lake.
• Hypothesis:A predicted solution to the question or problem.Example: If the plastic material is small, then it will degrade faster than a large particle.
• Experiment:A series of tests used to evaluate the hypothesis. Experiments consist of anindependent variablethat the researcher modifies and adependent variablethat changes due to the independent variable. They also include acontrol groupused as a standard to make comparisons.
  • Example: Collect plastic particles both onshore and offshore of the lake over time. Determine the size of the particles and describe the lake conditions during this time period.
• Observe:Analyze data collected during an experiment to observe patterns.
  • Example: Analyze the differences between the numbers of particles collected in terms of size.
• Conclusion:State whether the hypothesis is rejected or accepted and summarize all results.
• Communicate:Report findings so others can replicate and verify the results.

Robert Hooke discovered the first cells in the mid-eighteenth century. The cell theory is a theory because it is supported by a significant number of experimental findings. The cell theory took many years to be developed because microscopes were not powerful enough to make such observations.

This theory, or in-depth explanation, about cells consists of three parts:

• All living things are composed of one or more cells.
• Cells are alive and represent the basic unit of life.
• All cells are produced from pre-existing cells.

The protein disc that holds two sister chromatids together is what collectively makes a chromosome. A gene is a segment of DNA, deoxyribonucleic acid, which transmits information from parent to offspring. A single molecule of DNA has thousands of genes. A chromosome is a rod-shaped structure that forms when a single DNA molecule and its associated proteins coil tightly before cell division.

Chromosomes have two components:

• Chromatids: two copies of each chromosome
• Centromeres: protein discs that attach the chromatids together

Human cells have 23 sets of different chromosomes. The two copies of each chromosome are called homologous chromosomes, or homologues. An offspring receives one homologue from each parent. When a cell contains two homologues of each chromosome, it is termed diploid (2n). A haploid (n) cell contains only one homologue of each chromosome. The only haploid cells humans have are the sperm and eggs cells known as gametes.

The main male reproductive organs are thepenisand thetesticles, which are located external to the body. The penis is composed of a long shaft and a bulbous end called the glans penis. The glans penis is usually surrounded by an extension of skin called the foreskin.

Thetestes(analogous to the female ovaries), or testicles, are retained in a pouch of skin called thescrotum, which descends from the base of the penis. The scrotum contains nerves and blood vessels needed to support the testicles’ functions. Each testicle (or testis) produces sperm (analogous to the female ova), which are passed into a series of coiled tubules called theepididymis. The epididymis stores and nurtures sperm until they are passed into thevas deferens, a tubule that is about 30 centimeters long, extending from the testicle into the pelvis and ending at the ejaculatory duct.

The epididymis and vas deferens are supported by several accessory glands (the seminal vesicles, the prostate gland, and the Cowper glands) that produce fluid components of semen and support the sperm cells.

Atissueis a group of cells with similar structure and function and similar extracellular substances located between the cells. The table below describes the four primary tissues found in the human body.

body.

A neutralization reaction is a type of acid-base reaction where an acid and base react to form a salt and water.

In an aqueous solution, a base increases the hydroxide concentration (OH–), while an acid increases the hydrogen ion (H+) concentration. Sometimes,neutralization reactionsalso occur. This type of reaction happens when an acid and a base react with each other to form water and salt. Salt is typically defined as anionic compoundthat includes any cation except H+and any anion except OH–. Consider the following example of a neutralization reaction between hydrobromic acid (HBr) and potassium hydroxide (KOH).

HBr+KOH→KBr+H2O

Not all neutralization reactions proceed in the manner where all reactants are in the aqueous phase. In some chemical reactions, one reactant may be a solid. The neutralization reaction can still proceed to completion.

Human intercourse consists of the male introducing sperm into the female’s reproductive system. Sperm may then pass through the female’s reproductive system to the Fallopian tubes where one sperm fertilizes an ovum, creating azygote. The zygote passes out of the Fallopian tube and implants into the uterine wall to begin gestation. Over nine months, the zygote develops and grows into an embryo and then a fetus. An infant is the baby that is born.

Unlike condensation, deposition, and melting, evaporation is dependent not only on the temperature, but also on the amount of a substance available.

Condensationis the change of a gas or vapor to a liquid. A change in the pressure and the temperature of a substance causes this change. The condensation point is the same as the boiling point of a substance. It is most noticeable when there is a large temperature difference between an object and the atmosphere. Condensation is also the opposite of evaporation.

Evaporationis the change of a liquid to a gas on the surface of a substance. This is not to be confused with boiling, which is a phase transition of an entire substance from a liquid to a gas. The evaporation point is the same as the freezing point of a substance. As the temperature increases, the rate of evaporation also increases. Evaporation depends not only on the temperature, but also on the amount of substance available.

Freezingis the change of a liquid to a solid. It occurs when the temperature drops below the freezing point. The amount of heat that has been removed from the substance allows the particles of the substance to draw closer together, and the material changes from a liquid to a solid. It is the opposite of melting.

Meltingis the change of a solid into a liquid. For melting to occur, enough heat must be added to the substance. When this is done, the molecules move around more, and the particles are unable to hold together as tightly as they can in a solid. They break apart, and the solid becomes a liquid.

Sublimationis a solid changing into a gas. As a material sublimates, it does not pass through the liquid state. An example of sublimation is carbon dioxide, a gas, changing into dry ice, a solid. It is the reverse of deposition.

Depositionis a gas changing into a solid without going through the liquid phase. It is an uncommon phase change. An example is when it is extremely cold outside and the cold air comes in contact with a window. Ice will form on the window without going through the liquid state.

The particles in a sample of gas are farther apart than in solids or liquids and therefore have the lowest amount of cohesion.

• Cohesion is the tendency of particles of the same kind to stick to each other.
• A solid has the lowest amount of energy because its particles are packed close together. Liquids have more energy than a solid, and gases have more energy than solids or liquids because the cohesive forces are very weak.

If the cohesion between particles decreases, then the particles must be undergoing a phase change that allows particles to move farther apart. This happens when a substance vaporizes and turns from liquid to gas. Any phase change that moves to the right in the diagram above requires energy to be added to the system because the substance has more energy at the end of the phase change. The phase changes aremelting,vaporization (boiling), andsublimation. When energy is added, particles move faster and can break away from each other more easily as they move to a state of matter with a higher amount of energy. This is most commonly done by heating the substance.