Most of the nutrient absorption along the alimentary canal occurs in the

A. ascending colon

B. stomach

C. jejunum

D. ileum

Answer Explanation:

C. jejunum

- Correct: Most of the nutrient absorption along the alimentary canal occurs in the jejunum, which is the middle segment of the small intestine. The jejunum has a highly folded inner surface covered with finger-like projections called villi and even smaller microvilli. These structures greatly increase the surface area available for absorption. The epithelial cells lining the villi contain numerous transport proteins and enzymes responsible for absorbing nutrients such as carbohydrates, proteins, fats, vitamins, and minerals into the bloodstream for distribution to the body's cells.

A. ascending colon

- Incorrect: The ascending colon is part of the large intestine (colon) where water and electrolytes are primarily absorbed, but it is not a major site of nutrient absorption.

B. stomach

- Incorrect: While some substances, such as water, electrolytes, alcohol, and certain drugs, can be absorbed in small amounts in the stomach, the stomach is not a major site of nutrient absorption. Its main function is to begin the digestion of proteins and store food temporarily.

D. ileum

- Incorrect: The ileum is the final segment of the small intestine, and while it does participate in nutrient absorption, the majority of nutrient absorption occurs in the jejunum, which precedes the ileum along the alimentary canal. The ileum primarily absorbs bile salts, vitamin B12, and some remaining nutrients not absorbed in the jejunum.

Therefore, the Correct Answer is C.

Q #1: The graph below shows the effect of environmental temperature on a girl's skin temperature and on her internal body temperature. Which statement best describes what happens as environmental temperature increases from 20ºC to 30ºC?

A. Both the internal and the skin temperatures reach 40ºC.

B. Both the internal and the skin temperatures increase by about 7ºC.

C. The skin temperature decreases to about 30ºC.

D. The internal temperature increases by about 1ºC.

Answer Explanation

D) The internal temperature increases by about 1ºC.

- Correct: As environmental temperature increases from 20ºC to 30ºC, the body's internal temperature tends to increase slightly. This is due to the body's thermoregulatory mechanisms, which work to maintain a relatively constant internal temperature (around 37ºC or 98.6ºF) despite fluctuations in environmental temperature. When the environmental temperature rises, the body responds by increasing blood flow to the skin and by initiating mechanisms such as sweating to dissipate heat and maintain thermal equilibrium. However, the increase in environmental temperature may result in a slight increase in internal temperature, typically by about 1ºC, as the body works to dissipate excess heat.

A) Both the internal and the skin temperatures reach 40ºC.

- Incorrect: A 10ºC increase in environmental temperature from 20ºC to 30ºC is not likely to cause both internal and skin temperatures to reach 40ºC. Such a significant increase would likely lead to heatstroke or hyperthermia, which can be life-threatening.

B) Both the internal and the skin temperatures increase by about 7ºC.

- Incorrect: A 10ºC increase in environmental temperature is not likely to cause both internal and skin temperatures to increase by about 7ºC. Such a large increase in temperature would be excessive and would likely lead to severe heat-related illnesses.

C) The skin temperature decreases to about 30ºC.

- Incorrect: In response to an increase in environmental temperature, the body typically increases blood flow to the skin and initiates mechanisms such as sweating to dissipate heat. This would not result in a decrease in skin temperature to match the environmental temperature of 30ºC.
Q #2: Which human excretory organ breaks down red blood cells and synthesizes urea?

A. lung

B. kidney

C. skin

D. liver

Answer Explanation

D) liver

- Correct: The liver is the human excretory organ that breaks down red blood cells and synthesizes urea. Red blood cells have a finite lifespan and are continually replaced by new cells produced in the bone marrow. When old or damaged red blood cells are removed from circulation, their components are broken down by macrophages, primarily in the spleen and liver. The liver plays a crucial role in this process by breaking down hemoglobin, the oxygen-carrying protein in red blood cells, into heme and globin. Heme is further broken down into bilirubin, which is excreted in bile and eventually eliminated from the body in feces. Additionally, the liver synthesizes urea as a waste product of protein metabolism, which is excreted by the kidneys in urine.

A) lung

- Incorrect: While the lungs play a role in the excretion of carbon dioxide during respiration, they are not involved in breaking down red blood cells or synthesizing urea.

B) kidney

- Incorrect: The kidneys are responsible for filtering blood to remove waste products and excess substances, such as urea, creatinine, and electrolytes, to produce urine. While the kidneys excrete urea synthesized by the liver, they do not break down red blood cells.

C) skin

- Incorrect: The skin is involved in excreting certain waste products, such as sweat (containing water, electrolytes, and small amounts of urea and other metabolic waste), but it does not break down red blood cells or synthesize urea.
Q #3: Which of the following organs has 3 layers of smooth muscle in its muscularis externa?

A. small intestine

B. esophagus

C. stomach

D. large intestine

Answer Explanation

C. stomach

- Correct: The stomach has three layers of smooth muscle in its muscularis externa, which is the muscular layer of the gastrointestinal tract responsible for peristalsis and mixing of food. These muscle layers are arranged in longitudinal, circular, and oblique orientations, allowing for the mechanical processing of ingested food and the propulsion of food through the digestive tract. This muscular arrangement contributes to the stomach's ability to churn and mix food with gastric juices during digestion.

A. small intestine

- Incorrect: While the small intestine does have smooth muscle in its muscularis externa, it typically has two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.

B. esophagus

- Incorrect: The esophagus also has smooth muscle in its muscularis externa, but it typically has two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.

D. large intestine

- Incorrect: The large intestine, like the small intestine, typically has two layers of smooth muscle in its muscularis externa: an inner circular layer and an outer longitudinal layer.

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Most of the nutrient absorption along the alimentary canal occurs in the

More Questions on TEAS 7 Science

Q #1: The graph below shows the effect of environmental temperature on a girl's skin temperature and on her internal body temperature. Which statement best describes what happens as environmental temperature increases from 20ºC to 30ºC?

Answer Explanation

Q #2: Which human excretory organ breaks down red blood cells and synthesizes urea?

Answer Explanation

Q #3: Which of the following organs has 3 layers of smooth muscle in its muscularis externa?

Answer Explanation

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Most of the nutrient absorption along the alimentary canal occurs in the

More Questions on TEAS 7 Science

Q #1: The graph below shows the effect of environmental temperature on a girl&#39;s skin temperature and on her internal body temperature. Which statement best describes what happens as environmental temperature increases from 20&ordm;C to 30&ordm;C?

Answer Explanation

Q #2: Which human excretory organ breaks down red blood cells and synthesizes urea?

Answer Explanation

Q #3: Which of the following organs has 3 layers of smooth muscle in its muscularis externa?

Answer Explanation

Free Access on TEAS 7 Exams and Study Notes

TEAS 7 Exams (Q&A)

TEAS 7 Study Notes

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Refer a Friend

Q #1: The graph below shows the effect of environmental temperature on a girl's skin temperature and on her internal body temperature. Which statement best describes what happens as environmental temperature increases from 20ºC to 30ºC?