Simple cuboidal epithelial cells line the ducts of certain human exocrine glands. Various materials are transported into or out of the cells by diffusion. The formula for the surface area of a cube is 6 × S × S, and the formula for the volume of a cube is S × S × S, where S = the length of a side of a cube.
Structures which have a high surface area to volume ratio are better at facilitating diffusion. Based on this, which of the following cube-shaped cells would be most efficient in removing waste by diffusion?
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Cube (a).
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Cube (b).
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Cube (c).
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Cube (d).
This image shows a section from the small intestine. The vertical, stacked structures are microvilli, which absorb nutrients. Each microvillus is approximately 1 μm long by 0.1 μm in diameter.
Based on this picture, what advantage does having microvilli provide to an organism?
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Microvilli have a large surface area-to-volume ratio. This allows them to come in contact with nutrients easily.
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Microvilli have a small surface area-to-volume ratio. This there are more of them stacked in the same volume.
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Microvilli secrete enzymes that capture food particles as they pass over them. These enzymes are responsible for high absorption rates.
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Microvilli are warmer than the rest of the body. This temperature difference causes the microvilli to absorb nutrients rapidly.
As shown in this figure, the oral cavity has several components that contribute to ingestion and the initial stages of digestion. How do the components of the oral cavity work together to complete the first step of food processing?
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The teeth and jaw mechanically chew the food, and saliva from the salivary glands moistens the food and begins chemical digestion. The tongue then physically moves the food to the pharynx, where peristalsis moves the food into the stomach.
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The teeth and jaw mechanically chew the food, and saliva from the salivary glands moistens the food and initiates mechanical and chemical digestion. The tongue then physically moves the food to the pharynx, where peristalsis moves the food into the stomach.
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The teeth and jaw mechanically chew the food, and saliva from the salivary glands moistens the food and begins chemical digestion. The tongue then physically moves the food to the larynx, where peristalsis moves the food into the stomach.
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The teeth and jaw mechanically chew the food, and saliva from the salivary glands moistens the food and initiates mechanical and chemical digestion. The tongue then physically moves the food to the pharynx, where segmentation moves the food into the stomach.
This figure shows the majority of the digestive tracts of two organisms that consume different food sources. a. Which digestive tract belongs to the herbivore? b. How did you determine this?
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a. The digestive tract shown at the bottom belongs to the herbivore. b. Herbivores have a shorter intestinal tract, which allows stronger smooth muscle contractions called peristalsis in a shorter area, providing more opportunity for nutrients to be obtained and absorbed.
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a. The digestive tract shown at the top belongs to the herbivore. b. Herbivores have a longer intestinal tract, which provides more opportunity for nutrients to be obtained and absorbed, since plant material is difficult for animals to break down.
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a. The digestive tract shown at the bottom belongs to the herbivore. b. Herbivores have a longer intestinal tract, which provides more opportunity for the nutrients to react with the intestinal enzymes for better absorption, since plant material is difficult for animals to break down.
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a. The digestive tract shown at the bottom belongs to the herbivore. b. Herbivores have a shorter intestinal tract, which provides more opportunity for nutrients to be obtained and absorbed, since plant material is difficult for animals to break down.
This image shows the digestive systems of different animals.
Which animal is more likely to be a carnivore?
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Animal A.
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Animal B.
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Animal C.
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The diet of animals cannot be determined by their digestive systems.
This figure shows involuntary muscle movement in part of the digestive system. What stimulates this involuntary response?
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smelling food
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seeing food
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chewing food
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swallowing food
This image shows the digestive system of a ruminant animal. How does this polygastric digestive system enhance digestion efficiency in ruminants?
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Multiple stomach chambers in ruminant animals contain microbes that have cellulase, which breaks down plant material. Plant material is difficult to digest because animals lack cellulase to break down cellulose.
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Multiple stomach chambers in ruminant animals allow stronger smooth muscle contractions, which break down plant material. Plant material is difficult to digest because animals lack cellulase to break down cellulose.
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Multiple stomach chambers present in ruminant animals contain cellulase, which break down plant material. Plant material is difficult to digest because animals lack cellulase to break down cellulose.
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Multiple stomach chambers in ruminant animals allow the food to stay in the stomach for a longer time so that peristaltic movements and the action of enzymes on food particles occurs for a longer time.
Which option is a claim that can be made based on this study?
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The mice at 10°C had a higher rate of ATP production than the mice at 25°C.
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The mice at 10°C had a lower metabolic rate than the mice at 25°C.
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The mice at 25°C weighed less than the mice at 10°C.
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The mice at 25°C were more active than the mice at 10°C.
The image shows the structure of an ATP molecule.
When an ATP molecule is broken down for energy, which bonds break?
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The O—H bonds.
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The P—O bonds.
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The N—H bonds.
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The —O— bond.