Which choice best describes homeostasis?

A. Central

B. Parasympathetic

C. Somatic

D. Sympathetic

The autonomic nervous system is responsible for activities that are nonvoluntary and under unconscious control. This system controls glands and the smooth muscles of internal organs, heart rate, breathing, and digestion. The autonomic nervous system is further divided into the following:

• Sympathetic nervous system: The sympathetic nervous system focuses on emergency situations by preparing the body for fight or flight. (Sympathetic = Stress)
• Parasympathetic nervous system: The parasympathetic nervous system controls involuntary processes unrelated to emergencies. This system deals with “rest or digest” activities. (Parasympathetic = Peace)

The somatic nervous system primarily controls voluntary activities such as walking and riding a bicycle. Thus, this system sends information to the CNS and motor nerve fibers that are attached to skeletal muscle.

A. Ionic, because electrons are shared

B. Covalent, because electrons are shared

C. Ionic, because electrons are transferred

D. Covalent, because electrons are transferred

Nitrogen and oxygen are both nonmetals, which means they will share electrons in a covalent bond. For example, two oxygen atoms form a double bond, in which two pairs of electrons (four electrons total) are shared. Similarly, two nitrogen atoms form a molecule with a triple bond, in which three pairs of electrons (six electrons total) are shared. 

A. carbon dioxide

B. minerals in soil

C. decaying matter

D. sugar molecules

Autotrophs are organisms that use basic raw materials in nature, like the sun, to make energy-rich biomolecules. Minerals are naturally inorganic.

Autotrophs are organisms that make energy-rich biomolecules from raw material in nature. They do this by using basic energy sources such the sun. This explains why most autotrophs rely on photosynthesis to transform sunlight into usable food that can produce energy necessary for life. Plants and certain species of bacteria are autotrophs.

A. The height of a plant increases in the absence and presence of the nutrients

B. When the amount of nutrients available to the plant decreases, its height increases.

C. The amount of nutrients available to a plant is independent of how tall the plant gets

D. When the amount of nutrients available to the plant increases, its height also increases.

Because this is a positive correlation, if the nutrient concentration increases or decreases, plant height will either increase or decrease accordingly.

While analyzing data, scientists tend to observe cause-and-effect relationships. These relationships can be quantified using correlations. Correlations measure the amount of linear association between two variables. There are three types of correlations:

Positive correlation: 
As one variable increases, the other variable also increases. This is also known as a direct correlation.

Negative correlation: 
As one variable increases, the other decreases. The opposite is true if one variable decreases. A negative correlation is also known as an inverse correlation or an indirect correlation.

No correlation: 
There is no connection or relationship between two variables.

A. Nickel-32

B. Nickel-60

C. Germanium-56

D. Germanium-60

The number of protons, 28, gives the atomic number, which identifies this atom as nickel. The mass is the number after the dash in the isotope name, which is determined by adding the numbers of protons and neutrons (28 + 32 = 60).

A. A student reads about a new way to harness energy from the sun.

B. A researcher studies the effects of car exhaust on how people breathe.

C. A researcher analyzes how many plants respond well to a new fertilizer

D. A student discovers how insulin plays a role in the development of diabetes

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 the scientific 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 an independent variable that the researcher modifies and a dependent variable that changes due to the independent variable. They also include a control group used 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.

A. 14 protons, 14 neutrons, 18 electrons

B. 34 protons, 45 neutrons, 36 electrons

C. 35 protons, 44 neutrons, 35 electrons

D. 82 protons, 125 neutrons, 78 electrons

Because it has more protons than electrons, this atom has a positive charge and can be classified as a cation. When a metal such as sodium reacts to become stable, it loses its valence electrons. At first, it is a neutral atom with 11 protons and 11 electrons. When it loses an electron, the number of protons does not change, and the atom has 11 protons and 10 electrons. Because there is one more positively charged proton, a cation forms. A cation is an ion with a net positive charge.

A. Cognitive

B. Integrative

C. Motor

D. Sensory

A sensory nerve is a nerve that carries sensory signals from the external environment to the brain to the central nervous system. It is also an afferent nerve, long dendrites of sensory neurons, which sends sensory information towards the central nervous system (CNS). This information is what is sensed, using the five senses from external environment, sight, sound, smell, taste, and touch.

Motor nerves have only efferent fibers, long axons of motor neurons, that carry impulses away from the CNS to the effectors, which are typically tissues and muscles of the body.

Interneurons are nerve cells that act as a bridge between motor and sensory neurons in the CNS. These neurons help form neural circuits, which helps neurons communicate with each other.

A. S

B. G1

C. M

D. G2

A cell copies its DNA during the S phase, and nucleotides are the building blocks of DNA. Thus, the step preceding the S phase, the G1 phase, is the phase of the cell cycle when the cell would contain the most nucleotides.

For a cell to divide into more cells, it must grow, copy its DNA, and produce new daughter cells. The cell cycle regulates cellular division. This process can either prevent a cell from dividing or trigger it to start dividing.

The cell cycle is an organized process divided into two phases: interphase and the M (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 G2 phases make up interphase.

• G1: The first gap phase, during which the cell prepares to copy its DNA
• S: The synthesis phase, during which DNA is copied
• G2 : The second gap phase, during which the cell prepares for cell division

It may appear that little is happening in the cell during the gap phases. Most of the activity occurs at the level of enzymes and macromolecules. The cell produces things like nucleotides for synthesizing new DNA strands, enzymes for copying the DNA, and tubulin proteins for building the mitotic spindle. During the S phase, the DNA in the cell doubles, but few other signs are obvious under the microscope. All the dramatic events that can be seen under a microscope occur during the M phase: the chromosomes move, and the cell splits into two new cells with identical nuclei.

A. mouth

B. esophagus

C. ileum

D. colon

Oral Cavity is the first part of the digestive system. It is bounded by the lips and cheeks and contains the teeth and tongue. Its primary function is to masticate, or chew, and moisten the food.

Pharynx, or throat, connects the mouth to the esophagus.

Esophagus is a muscular tube about 25 centimeters long. Food travels down it to the cardiac sphincter of the stomach.

Pyloric sphincter. The exit of the stomach.

Small intestine is about 6 meters long and consists of three parts: duodenum, jejunum, and ileum.

Large intestine, consists of the cecum, colon, rectum, and anal canal. The cecum is located where the small and large intestine meet. The primary function of the large intestine is to compress the waste and collect any excess water that can be recycled.

Colon is about 1.5 to 1.8 meters long and consists of four parts: the ascending, transverse, descending, and sigmoid colon.