Cisco
CompTIA
ISC
EC-Council
EXIN
Fortinet
ITIL
Juniper
Microsoft
VMware
Avaya
SAP
Google
NVIDIA
Salesforce
Amazon
Palo Alto Networks
ISC2
Splunk
ServiceNow
All Vendors
  2. Home
  3. Exams
  4. Test Prep
  5. MCAT Test

Test Prep MCAT Test Exam
Medical College Admission Test: Verbal Reasoning, Biological Sciences, Physical Sciences, Writing Sample (Page 14 )

Updated On: 12-Jan-2026
Page 14 of 164
PDF with 811 Questions

Which of the following species exists as a resonance hybrid?

  1. HCN
  2. H2CO3
  3. NO2-
  4. ClO-

Answer(s): C

Explanation:

A resonance hybrid is a molecule that cannot be represented by just one Lewis structure; the molecule is said to be a composite of the possible structures. Choice A is wrong because all the atoms have a complete octet ­ hydrogen having its two electrons ­ and only one Lewis structure is possible:

Choice B is wrong because it too has only one structure:

Choice C is correct because it does exist as a resonance hybrid:

Keep in mind that the nitrite ion does not exist as one or the other of the above resonance structures but is a composite of them, having a structure somewhere in-between the two. Choice D is wrong because it has only one Lewis structure as well:



An automobile reaches a velocity of 30 m/s after accelerating at 4 ms-2 for 5 seconds. What was its initial velocity?

  1. -10 m/s
  2. 0 m/s
  3. 10 m/s
  4. 20 m/s

Answer(s): C

Explanation:

vf = vi + at
30 = vi + (4 × 5)
30 = vi + 20
vi = 10 m/s



When the temperature of an iron bar is raised, its length expands. If the temperature of a second iron bar, which is initially twice as long as the first bar, is raised by twice as much, what is the ratio of the change in length of the first bar to the change in length of the second bar?

  1. 1:1
  2. 1:2
  3. 1:4
  4. 2:1

Answer(s): C

Explanation:

To answer the question, apply the formula for the thermal expansion of a solid. This formula is given by L = LT , where L is the change in length, L is the original length, T is the change in temperature, and is some constant which depends on the type of material. This formula makes sense intuitively: as the length increases, there is more material available to expand, and as the temperature increases, the more vigorously the material expands.
Compared with the first iron bar, the second iron bar is twice as long, so L2 = 2L1 , and is raised twice as much in temperature, so T2 = 2 T1. Note that is the same for both bars because they are made of the same material. Therefore, the ratio of the first bar's length change to the second bar's length change is



Historically, two different methods have been used to estimate the fluid pressure in capillary beds.
Method 1
A glass pipette is inserted into the capillary. The level of blood rising in the pipette is measured and used to calculate the pressure. Alternatively, an inert fluid of density can be placed in the pipette and its height h can be measured. The pressure in the capillary is given by gh, where g is the acceleration due to gravity.


Figure 1
Method 2
The pressure can be measured indirectly in the following way. A section of gut tissue is removed from a specimen and placed on a beam balance. Blood is circulated through the tissue by a pump. The arterial pressure is then decreased. This leads to a decrease in the capillary hydrostatic pressure in the gut capillaries. The constant osmotic pressure of plasma proteins in the capillary causes absorption of fluid from the gut section which will decrease its weight. To prevent a change in the weight of the gut section, the venous pressure is increased. This tends to increase the capillary pressure, reducing the flow of fluid from the gut tissue into the capillaries. The capillary pressure is thus held constant (and the balance kept level) as the arterial pressure is decreased and the venous pressure increased. The arterial and venous pressures meet at the capillary pressure being measured.
( = MRT, where is the osmotic pressure, M the molarity of the solutes, R the universal gas constant, and T the temperature in Kelvin.)

Figure 2
An arteriole is almost completely blocked by a blood clot as shown below. At which point will the velocity of blood flow be the greatest? (Assume ideal laminar flow throughout.)

  1. A
  2. B
  3. C
  4. D

Answer(s): B

Explanation:

The stem says to assume laminar flow, indicating that we should consider the blood as a simple homogeneous fluid. Using the continuity equation it is clear that the greatest velocity will occur in the region of smallest cross sectional area.
Continuity equation: v1A1 = v2A2, where v is the velocity, A is the cross-sectional area.
Note that following the divergence of the arteriole into two branches, the total cross-sectional area has not changed greatly so the velocity in each branch will not be different from the velocity at C.
Choices A, C, and D are incorrect because the cross-sectional area is greater for each than at B, so the velocity at these locations is lower.



Historically, two different methods have been used to estimate the fluid pressure in capillary beds.
Method 1
A glass pipette is inserted into the capillary. The level of blood rising in the pipette is measured and used to calculate the pressure. Alternatively, an inert fluid of density can be placed in the pipette and its height h can be measured. The pressure in the capillary is given by gh, where g is the acceleration due to gravity.


Figure 1
Method 2
The pressure can be measured indirectly in the following way. A section of gut tissue is removed from a specimen and placed on a beam balance. Blood is circulated through the tissue by a pump. The arterial pressure is then decreased. This leads to a decrease in the capillary hydrostatic pressure in the gut capillaries. The constant osmotic pressure of plasma proteins in the capillary causes absorption of fluid from the gut section which will decrease its weight. To prevent a change in the weight of the gut section, the venous pressure is increased. This tends to increase the capillary pressure, reducing the flow of fluid from the gut tissue into the capillaries. The capillary pressure is thus held constant (and the balance kept level) as the arterial pressure is decreased and the venous pressure increased. The arterial and venous pressures meet at the capillary pressure being measured.
( = MRT, where is the osmotic pressure, M the molarity of the solutes, R the universal gas constant, and T the temperature in Kelvin.)

Figure 2
Assume that a mass (m) of 0.2 kg is placed 25 cm to the right of the fulcrum. A section of gut, initially weighing 0.1 kg is placed 50 cm to the left of the fulcrum. During the experiment, the mass m is seen to descend. In order to maintain the balance level the following action should be taken:

  1. the mass m should be moved away from the fulcrum.
  2. the arterial pressure should be decreased.
  3. the venous pressure should be increased.
  4. an inert fluid with higher density than that of blood should be used in the pipette.

Answer(s): C

Explanation:

According to the passage, when fluid flows out of the gut (because the hydrostatic pressure in the capillary bed is lower than the osmotic pressure), the gut will become lighter and will ascend. Thus, the mass m will descend.
The question stem indicates that the section of gut has become lighter. Fluid must be returned to the gut section to make it heavier and maintain the balance level. Increasing the venous pressure will increase the hydrostatic pressure in the capillary bed, leading to flow of fluid from the capillary into the gut section. Note that no quantitative analysis (calculation) is necessary to answer this question. Choice A is incorrect because moving the mass m away from the fulcrum will increase the distance between the force applied and the fulcrum, thus increasing the torque produced by the mass m causing it to descend more. The equation for torque is shown below:
= Fr sin , where F is the magnitude of the force applied, r is the distance between the force and the torque fulcrum, is the angle between the force and the vector r.
Choice B is incorrect because decreasing the arterial pressure will decrease the hydrostatic pressure in the capillary bed causing more fluid to be lost from the gut. The gut will become lighter and will ascend, causing the mass m to descend more. Choice D is a distractor choice: the pipette (from Method 1) does not come into play in this set-up, which deals with Method 2.



Viewing page 14 of 164
Viewing questions 66 - 70 out of 811 questions



Post your Comments and Discuss Test Prep MCAT Test exam prep with other Community members:

Join the MCAT Test Discussion