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
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.
Therefore, the Correct Answer is D.
More Questions on TEAS 7 Science
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Q #1: The sequence of amino acids in a gene determines
A. the primary structure of a codon
B. the primary structure of a protein
C. the primary structure of a nucleotide
D. the primary structure of a nucleic acid.
Answer Explanation
The sequence of amino acids in a gene determines the primary structure of a protein. The components necessary for translation are located in the cytoplasm. Translation is the making of proteins by mRNA binding to a ribosome with the start codon that initiates the production of amino acids. A peptide bond forms and connects the amino acids together. The sequence of amino acids determines the protein’s structure, which determines its function.
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Q #2: Which of the following are included in the male reproductive system?
A. the penis and epididymis
B. the vas deferens and uterus
C. the penis and Fallopian tubes
D. the penis, scrotum, and cervix
Answer Explanation
The main male reproductive organs are the penis and the testicles, 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.
The testes (analogous to the female ovaries), or testicles, are retained in a pouch of skin called the scrotum, 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 the epididymis. The epididymis stores and nurtures sperm until they are passed into the vas 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.
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Q #3: What phase is the cell cycle part of?
A. Interphase
B. Metaphase
C. Prophase
D. Telophase
Answer Explanation
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: 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.
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Q #4: An intracellular chemical signal can be produced in the cell membrane. Once it is produced, where does it go?
A. To a different cell
B. To another part of the same cell
C. To a region right outside the cell
D. To an area with a high ion concentration
Answer Explanation
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.
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Q #5: Which of the following atoms is a cation?
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
Answer Explanation
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.
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Q #6: During the aging process, not all hormone levels decrease; some actually increase. Which of the following is a hormone that may increase as a person ages?
A. Cortisol
B. Insulin
C. Luteinizing
D. Thyroid
Answer Explanation
The aging process affects hormone activity in one of three ways: their secretion can decrease, remain unchanged, or increase.
Hormones that decrease secretion include the following:
- Estrogen (in women)
- Testosterone (in men)
- Growth hormone
- Melatonin
In women, the decline in estrogen levels leads to menopause. In men, testosterone levels usually decrease gradually. Decreased levels of growth hormone may lead to decreased muscle mass and strength. Decreased melatonin levels may play an important role in the loss of normal sleep-wake cycles (circadian rhythms) with aging.
Hormones that usually remain unchanged or slightly decrease include the following:
- Cortisol
- Insulin
- Thyroid hormones
Hormones that may increase secretions levels include the following:
Parathyroid hormone
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Norepinephrine
- Epinephrine, in the very old
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Q #7: Which choice best describes homeostasis?
A. A functional system of the body
B. Blood flow to every cell in the body
C. A relatively constant environment within the body
D. Neural pathways that have integrated into the body
Answer Explanation
Homeostasis is the existence and maintenance of a relatively constant environment within the body. Each cell of the body is surrounded by a small amount of fluid, and the normal functions of each cell depend on the maintenance of its fluid environment within a narrow range of conditions, including temperature, volume, and chemical content. These conditions are known as variables. For example, body temperature is a variable that can increase in a hot environment or decrease in a cold environment.
There are two types of feedback mechanisms in the human body: negative and positive.
- Negative Feedback: Most systems of the body are regulated by negative feedback mechanisms, which maintain homeostasis. Negative means that any deviation from the set point is made smaller or is resisted. The maintenance of normal blood pressure is a negative-feedback mechanism. Normal blood pressure is important because it is responsible for moving blood from the heart to tissues.
- Positive Feedback: Positive-feedback mechanisms are not homeostatic and are rare in healthy individuals. Positive means that when a deviation from a normal value occurs, the response of the system is to make the deviation even greater. Positive feedback therefore usually creates a cycle leading away from homeostasis and, in some cases, results in death. Inadequate delivery of blood to cardiac muscle is an example of positive feedback.
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Q #8: After food has been masticated in the oral cavity, where does it go next?
A. Colon
B. Liver
C. Pancreas
D. Pharynx
Answer Explanation
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.
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Q #9: Which is classified as a type of acid-base reaction that produces a salt?
A. Combination
B. Decomposition
C. Hydrolysis
D. Neutralization
Answer Explanation
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 reactions also 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 an ionic compound that 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.
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Q #10: A person is diagnosed as having acidosis, a condition in which the blood pH is below 7.45. What does the doctor most likely conclude?
A. Too much carbon dioxide is found in the blood.
B. Highly oxygenated blood circulates through the body
C. A blockage prevents blood from leaving the pulmonary artery
D. The nasal cavity has a difficult time clearing particles from the air.
Answer Explanation
Acidosis is when the body fluids contain too much acid, or low pH. The kidneys and lungs are unable to keep the body’s pH in balance. Acidosis is the result when there is too much loss of bicarbonate from the blood known as metabolic acidosis, or due to a buildup of carbon dioxide in the blood due to poor lung function, known as respiratory acidosis. It is the opposite of alkalosis, which is a condition in which there is too much base in the body fluids.
