What structure plays a role in air conduction?
A. Alveolus
B. Capillary
C. Lung
D. Trachea
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.
Therefore, the Correct Answer is D.
More Questions on TEAS 7 Science
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Q #1: The diffusion of nutrients through the walls of the digestive system is critical to homeostasis in the body. Where does the majority of this diffusion take place in the digestive system?
A. Stomach
B. Esophagus
C. Oral cavity
D. Small intestine
Answer Explanation
The duodenum is the first part of the small intestines, located between the stomach and the middle part of the small intestines (jejunum). Once food has mixed with acid in the stomach, it moves into the duodenum, where it then mixes with bile from the gallbladder and digestive juices secreted from the pancreas. In the duodenum, absorption of vitamins, minerals, and nutrients begins.
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Q #2: In which state of matter do the particles of iron have the lowest amount of cohesion?
A. Solid iron particles have the lowest amount of cohesion
B. Liquid iron particles have the lowest amount of cohesion
C. Gaseous iron particles have the lowest amount of cohesion
D. The particles have the same amount of cohesion in all states of matter.
Answer Explanation
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.
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Q #3: When would a cell most likely contain the most nucleotides?
A. S
B. G1
C. M
D. G2
Answer Explanation
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.
