During which of the following phase changes will the cohesion between the particles in a substance decrease?

Once the food has been masticated in the oral cavity (mouth), it is then swallowed and travels back into the pharynx down into the esophagus, which leads into the stomach.

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.

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.

The primary function of the respiratory system is to provide oxygen to and remove carbon dioxide from the body. In addition to gas exchange, the respiratory system enables a person to breathe. Breathing, or inhalation, is essential to life. It is the mechanism that provides oxygen to the body. Without oxygen, cells are unable to perform their functions necessary to keep the body alive. The primary muscle of inspiration is the diaphragm. Known as the chest cavity, this dome shaped structure flattens when it contracts. The rib cage moves outward, allowing outside air to be drawn into the lungs. During relaxation, the diaphragm returns to its dome shape and the rib cage moves back to its natural position. This causes the chest cavity to push air out of the lungs.

The respiratory system can be functionally divided into two parts:

• Air-conducting portion: Air is delivered to the lungs. This region consists of the upper and lower respiratory tract—specifically, the larynx, trachea, bronchi, and bronchioles.
• Gas exchange portion: Gas exchange takes place between the air and the blood. This portion includes the lungs, alveoli, and capillaries.

Inductive reasoning involves making specific observations and using them to make broad statements. The student observes that all of the tigers have the same stripe pattern. He can use this observation to make the broad statement that all the tigers’ offspring will have the same stripe pattern.

Inductive reasoninginvolves drawing a general conclusion from specific observations. This form of reasoning is referred to as the “from the bottom up” approach. Information gathered from specific observations can be used to make a general conclusion about the topic under investigation. In other words, conclusions are based on observed patterns in data.

The phenotype is the physical appearance of an organism, and the genotype is the set of alleles.

Mendel’s Theory of Heredity

To explain his results, Mendel proposed a theory that has become the foundation of the science of genetics. The theory has five elements:

• Parents do not transmit traits directly to their offspring. Rather, they pass on units of information calledgenes.
• For each trait, an individual has two factors: one from each parent. If the two factors have the same information, the individual ishomozygousfor that trait. If the two factors are different, the individual isheterozygousfor that trait. Each copy of a factor, orgene, is called anallele.
• The alleles determine the physical appearance, orphenotype. The set of alleles an individual has is itsgenotype.
• An individual receives one allele from each parent.
• The presence of an allele does not guarantee that the trait will be expressed

Before mitosis or meiosis occurs, interphase must happen. This is when the cell cycle takes place. The cell cycle is an organized process divided into two phases:interphaseand theM (mitotic) phase. During interphase, the cell grows and copies its DNA. After the cell reaches the M phase, division of the two new cells can occur. The G1, S, and G2phases make up interphase.

A control group is a factor that does not change during an experiment. Due to this, it is used as a standard for comparison with variables that do change such as a dependent variable.

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.

Because more solute could be added and dissolve, the solution has not yet reached its limit and is considered unsaturated. Because all the solute dissolves, the particles in the mixture are evenly distributed as a homogenous mixture.

• Amixtureis when elements and compounds are physically, but not chemically, combined.
• Ahomogeneousmixture is when substances mix evenly and it is impossible to see individual components. Aheterogeneousmixture is when the substances mix unevenly and it is possible to see individual components.
• Asolutionis a type of homogeneous mixture that is formed when a solute dissolves in a solvent.
• The concentration of a solution is the amount of a substance in a given amount of solution. Anunsaturatedsolution has the ability to dissolve more solute and asaturatedsolution has already reached the limit of solute it can dissolve.

There are two major types of receptor molecules that respond to an intercellular chemical signal:

• Intracellular receptors: These receptors are located in either the cytoplasm or the nucleus of the cell. Signals diffuse across the cell membrane and bind to the receptor sites on intracellular receptors, of the same cell.
• Membrane-bound receptors: These receptors extend across the cell membrane, with their receptor sites on the outer surface of the cell membrane. They respond to intercellular chemical signals that are large, water-soluble molecules that do not diffuse across the cell membrane.