Question 1

In an experiment to test the effect of a new weight loss drug, half of the people in the study received the drug, and the other half received a placebo (a pill that has no physiological effect). In addition, only males from the ages of 20 to 25 were selected to participate in the study. All participants received their treatments (drug or placebo) every day for 4 weeks. Which of the following components of the study design served as the control group?
A) The 4-week length of the experiment.
B) The restriction of study participants in age and gender.
C) The participants who received a placebo.
D) The participants who received the drug.

Accepted Answer

The control group in this experiment is the group of participants who received the placebo, as this group allows for a comparison of the effects of the drug with the effects of no treatment. The other options (A, B, and D) do not serve as control groups. Option A is simply a feature of the design, option B is a restriction that was imposed for the purposes of the study, and option D was the treatment group being tested.

Question 2

Hyperthyroidism treatment in cats usually involves antithyroid medication or the use of radioactive iodine to destroy the abnormal (overactive) tissue growing in the thyroid gland. Surgery to remove the abnormal tissue is generally not advised, as the surgery could also accidentally destroy parathyroid tissue. The parathyroid gland releases a hormone called PTH that increases blood calcium levels. Based on your knowledge of homeostasis, predict why surgery is ill-advised.
A) Blood calcium levels would reach abnormally low levels if there is a lack of PTH.
B) Blood calcium levels would reach abnormally high levels if there is a lack of PTH.
C) Positive feedback will not be able to compensate for any problems caused by negative feedback.
D) A lack of PTH disrupts positive feedback control of blood calcium levels.

Accepted Answer

The parathyroid gland releases a hormone called PTH that increases blood calcium levels. If the parathyroid tissue is accidentally destroyed during surgery, there will be a lack of PTH leading to abnormally low levels of blood calcium. This disrupts homeostasis and can cause serious health problems for the cat.

Question 3

Which layer of the skin lacks connective tissue?
A) epidermis
B) dermis
C) hypodermis
D) hair

Accepted Answer

The answer of Which layer of the skin lacks connective...

Question 4

You are looking at a tissue under a microscope. You see mostly densely packed fibers with some cells scattered throughout. You would predict that the function of this tissue is to
A) attach bones to muscles or other bones.
B) connect epithelia to underlying tissues.
C) conduct electrical impulses.
D) produce voluntary movements of the body.

Accepted Answer

The description of tissue with densely packed fibers and some cells scattered throughout is characteristic of connective tissue, specifically types like tendons and ligaments. These structures primarily function to attach bones to muscles or other bones, facilitating movement and providing structural support.

Question 5

Structure in the living world is organized into hierarchical levels. Which of the following correctly lists these from least inclusive to most inclusive?
A) neuron, nervous system, nerve tissue, human
B) neuron, nerve tissue, brain, nervous system, human
C) neuron, brain, nervous system, nerve tissue, human

Accepted Answer

The correct order from least inclusive to most inclusive is:
neuron, nerve tissue, nervous system, brain, human. Choice B is the only option that follows this order. Choice A is incorrect because it places the nervous system before nerve tissue. Choice C is incorrect because it places the brain before the nervous system.

Question 6

Which of the following is most likely to be responsible if, when your blood sugar level rises, the level of sugar goes back down to a set point?
A) a malfunction in a homeostatic mechanism based on negative feedback
B) a homeostatic mechanism based on negative feedback
C) a malfunction in a homeostatic mechanism based on positive feedback
D) a homeostatic mechanism based on positive feedback

Accepted Answer

Homeostatic mechanisms based on negative feedback are responsible for maintaining a set point by counteracting any deviations from that set point. In this case, if blood sugar levels rise, negative feedback mechanisms would work to bring them back down to the set point. Malfunctions in these negative feedback mechanisms could lead to a failure to maintain the set point, but they are still the most likely explanation for its regulation. Homeostatic mechanisms based on positive feedback, on the other hand, would amplify rather than counteract any deviations from the set point, and are therefore less likely to be responsible for maintaining a stable blood sugar level.

Question 7

Which of the following indicates a poorly designed study?
A) a control group
B) variables were controlled
C) bias
D) follow-up studies

Accepted Answer

Bias indicates a poorly designed study because it can lead to inaccurate or unreliable results. The other options (A, B, D) are all indicative of a well-designed study.

Question 8

Imagine an invertebrate that lives in an estuary where salinity varies cyclically with the tides. If this individual is able to adjust the salt concentration of its body fluids, its salt concentration will have
A) slight fluctuations that are kept within a narrow range.
B) irregular fluctuations that range from large to small.
C) a cyclic fluctuation opposite that of the surrounding water.
D) a cyclic fluctuation depending upon when the animal drinks.

Accepted Answer

If the individual is able to adjust the salt concentration of its body fluids, it will be able to maintain a relatively constant internal salt concentration despite the fluctuations in the surrounding water. This will result in only slight fluctuations that are kept within a narrow range.

Question 9

If the epithelium that lines the air sacs of your lungs were to gain a layer of cells, which of the following would likely occur to the rate of oxygen diffusion?
A) Oxygen will diffuse across the lung surface more quickly.
B) Oxygen will diffuse across the lung surface more slowly.
C) Oxygen will diffuse across the lung surface out of, instead of into, the body.
D) Oxygen will diffuse across the lung surface at a normal rate because it is only the shape of the cells that affect diffusion rate.

Accepted Answer

Adding a layer of cells to the epithelium lining the air sacs of the lungs would increase the diffusion distance that oxygen must travel to reach the bloodstream. This increased distance would slow down the rate of oxygen diffusion.

Question 10

The vertebrate kidney helps to keep the acidity of body fluids constant by varying the amount of hydrogen ions (H+) it secretes into the urine. You can confidently predict that this aspect of kidney function will be controlled by
A) a positive feedback mechanism.
B) a negative feedback mechanism.
C) nerve impulses from the brain.
D) a hormone produced in the kidney itself.

Accepted Answer

Negative feedback mechanisms are used to maintain homeostasis within the body. In this case, if the acidity of the body fluids increases, the kidney will secrete more H+ ions into the urine, thus decreasing the acidity of the body fluids. This process is regulated by a negative feedback mechanism, as it helps maintain a stable level of acidity in the body.

Question 11

You are looking at a sample of epithelial tissue under a microscope. What would you look for to determine the type of epithelium you are viewing?
A) the number of cell layers
B) the shape of the cells
C) the color of the cells
D) the number of cell layers and the shape of the cells

Accepted Answer

The number of cell layers and the shape of the cells are the two main characteristics used to classify epithelial tissue. The number of cell layers is used to determine if it is simple or stratified, while the shape of the cells determines if it is squamous, cuboidal, or columnar. Therefore, looking at both of these characteristics would allow us to determine the type of epithelium being viewed. The color of the cells is not a relevant characteristic in determining epithelial tissue type.

Question 12

Materials such as food, minerals, and oxygen are passed to cells through
A) water.
B) interstitial fluid.
C) matrix fibers.
D) neurons.

Accepted Answer

Interstitial fluid is the extracellular fluid found in the spaces between cells and tissues. It is responsible for transporting nutrients, gases, and other essential materials to cells. Water, matrix fibers, and neurons do not play a direct role in the transport of materials to cells.

Question 13

Most homeostasis depends on
A) positive feedback control.
B) negative feedback control.
C) the size of cells.
D) predictable environmental conditions.

Accepted Answer

Homeostasis is the maintenance of a stable internal environment within an organism. Negative feedback control is a mechanism by which the body maintains homeostasis. When a deviation from the optimum level occurs, a corrective response is activated that counteracts the deviation, returning the system to its original state. This is the primary mechanism responsible for maintaining homeostasis in the body. Positive feedback control, on the other hand, amplifies the deviation from the optimum level, making it more difficult to return to homeostasis. The size of cells and environmental conditions may affect homeostasis, but they are not the primary mechanism responsible for it.

Question 14

Bioengineering to create organs for transplants involves
A) growing cells without a scaffold.
B) seeding a scaffold of connective tissue matrix with stem cells.
C) transplanting unaltered organs.
D) using 3D printers to make organs that function without copying structure.

Accepted Answer

Bioengineering to create organs for transplants typically involves seeding a scaffold of connective tissue matrix with stem cells. This allows the cells to grow and form the necessary structure and function of the organ. Growing cells without a scaffold or using 3D printers to make organs without copying structure are also being explored, but are not currently common approaches. Transplanting unaltered organs is a traditional method of organ transplantation, but there are not enough donor organs available to meet the needs of all patients, hence the need for alternative approaches such as bioengineering.

Question 15

After you swallow the first bite of your food, your stomach becomes active. Polypeptides in the ingested food stimulate the stomach to release acid and enzymes, which creates more polypeptides. This greater concentration of polypeptides stimulates the stomach to release even more acid and enzymes, which continues until the contents of the stomach pass into the next digestive chamber. This phenomenon is best explained by
A) positive feedback control.
B) the relationship between structure and function.
C) how evolution does not lead to a perfect animal form.
D) how different tissues form an organ.

Accepted Answer

The phenomenon of the stomach releasing more acid and enzymes in response to the increasing concentration of polypeptides is an example of positive feedback control, as the initial stimulus (polypeptides) leads to an amplification of the response (more acid and enzymes).

Question 16

One of the functions of skin is the synthesis of vitamin D. Which of the following would be evidence for this function?
A) Vitamin D levels are higher in people who take supplements, such as multivitamins.
B) Vitamin D levels are lower in people who wear sunscreen.
C) Cancer rates are higher in people with more sun exposure.
D) People living in the tropics are vitamin D deficient.

Accepted Answer

Sunscreen blocks UVB radiation, the same radiation necessary for the synthesis of Vitamin D in the skin. Therefore, people who wear sunscreen are less likely to produce Vitamin D and have lower levels.

Question 17

The human wrist is very agile, but because of this agility it is also very prone to injuries involving the tissue connecting the wrist bones. This statement illustrates that animal structures
A) fit their functions and that nervous tissue can be damaged.
B) fit their functions and that muscle tissue can be damaged.
C) are not perfect and that muscle tissue can be damaged.
D) are not perfect and that connective tissue can be damaged.

Accepted Answer

The statement suggests that the connective tissue connecting the wrist bones is prone to injuries due to the agility of the human wrist. Therefore, animal structures are not perfect and connective tissue can be damaged.

Question 18

Dialysis is a treatment that can replace kidney function in some patients with kidney failure, while they await transplantation. Based on your knowledge of kidney function, how do you expect dialysis to work?
A) Dialysis extracts metabolic wastes from the blood.
B) Dialysis exchanges gases between the blood and the atmosphere.
C) Dialysis delivers nutrients to the blood.
D) Dialysis produces heat in the blood.

Accepted Answer

Dialysis works by removing metabolic waste from the blood, such as urea and creatinine, which are normally filtered by the kidneys. During dialysis, blood is filtered through a semipermeable membrane that allows waste products to be removed while leaving important nutrients and blood cells in the blood.

Question 19

Homeostasis
A) is the maintenance of a relatively constant internal state.
B) results from hormone imbalance.
C) occurs when the external environment changes to match the internal environment.
D) is the way the internal environment influences the external environment.

Accepted Answer

Homeostasis is the maintenance of a relatively constant internal state, regardless of changes in the external environment. Hormone imbalance can disrupt homeostasis, but it is not the cause of homeostasis. Homeostasis does not occur when the external environment changes to match the internal environment, but rather the opposite. Homeostasis is not the way the internal environment influences the external environment, but rather the way the body maintains balance within itself.

Question 20

When body temperature is too high, which of the following occurs?
A) Hypothalamus ceases to function.
B) Blood vessels in the skin dilate.
C) Capillaries contract.
D) Skeletal muscles contract.

Accepted Answer

When body temperature is too high, blood vessels in the skin dilate (expand). This allows more blood to flow near the surface of the skin, where it can release heat to the environment through radiation and convection. This helps to cool the body down. The hypothalamus actually plays a crucial role in regulating body temperature, so it does not cease to function. Capillaries do not contract in response to high body temperature, and skeletal muscles may or may not contract depending on the specific circumstances.

Quiz 20: Unifying Concepts of Animal Structure and Function

Which layer of the skin lacks connective tissue?

You are looking at a tissue under a microscope. You see mostly densely packed fibers with some cells scattered throughout. You would predict that the function of this tissue is to

Structure in the living world is organized into hierarchical levels. Which of the following correctly lists these from least inclusive to most inclusive?

Which of the following is most likely to be responsible if, when your blood sugar level rises, the level of sugar goes back down to a set point?

Which of the following indicates a poorly designed study?

Imagine an invertebrate that lives in an estuary where salinity varies cyclically with the tides. If this individual is able to adjust the salt concentration of its body fluids, its salt concentration will have

If the epithelium that lines the air sacs of your lungs were to gain a layer of cells, which of the following would likely occur to the rate of oxygen diffusion?

The vertebrate kidney helps to keep the acidity of body fluids constant by varying the amount of hydrogen ions (H+) it secretes into the urine. You can confidently predict that this aspect of kidney function will be controlled by

You are looking at a sample of epithelial tissue under a microscope. What would you look for to determine the type of epithelium you are viewing?

Materials such as food, minerals, and oxygen are passed to cells through

Most homeostasis depends on

Bioengineering to create organs for transplants involves

One of the functions of skin is the synthesis of vitamin D. Which of the following would be evidence for this function?

The human wrist is very agile, but because of this agility it is also very prone to injuries involving the tissue connecting the wrist bones. This statement illustrates that animal structures

Dialysis is a treatment that can replace kidney function in some patients with kidney failure, while they await transplantation. Based on your knowledge of kidney function, how do you expect dialysis to work?

Homeostasis

When body temperature is too high, which of the following occurs?