The measurement indicated by the line across the center of the cell is best referred to as which of the following?

A. Area.

B. Diameter.

C. Volume.

D. Radius.

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Answer Explanation:

Diameter.

The diameter is the measurement of a straight line passing through the center of a circle and connecting two points on its circumference.

In this case, the line across the center of the cell represents the diameter of the cell.

 

Choice A, Area, is not the correct answer because area refers to the amount of space inside a two-dimensional shape.

Choice C, Volume, is not the correct answer because volume refers to the amount of space occupied by a three-dimensional object.

Choice D, Radius, is not the correct answer because radius refers to the distance from the center of a circle to its circumference and is half the length of the diameter.

Therefore, the Correct Answer is B.

More Questions on TEAS 7 Science Exam 2

Question 1:

Which of the following microorganisms lack their own metabolic pathways and can only reproduce inside of a host cell?

A. Bacteria

B. Protozoa

C. Helminths

D. Viruses

The Correct Answer is D.

Viruses.

Viruses lack essential machinery needed to reproduce by themselves.

In fact, viruses can only reproduce after infecting a living cell - a process called viral replication.

Once inside a living cell, viruses re-program the cell’s machinery to produce viral proteins and genetic material to make new copies of themselves.

 

Choice A, Bacteria, is not the correct answer because bacteria have their own metabolic pathways and can reproduce outside of a host cell.

Choice B, Protozoa, is also not the correct answer because protozoa are singlecelled eukaryotes that have their own metabolic pathways and can reproduce outside of a host cell.

Choice C, Helminths, is not the correct answer because helminths are multicellular parasitic worms that have their own metabolic pathways and can reproduce outside of a host cell.


Question 2:

In the following data table of an experiment carried out at 4°C (39.2 F) over 4 hours 

Solution in bag

Solution outside bag

Bag mass change (g):

water

Water

-0.2

20% sucrose

Water

+2.4

, 40% sucrose

Water

+4.3

, 60% sucrose

water

+5.8

 

Which of the following options represents the dependent variable? 

A. Duration

B. Temperature

C. Bag mass change

D. Solution used outside

The Correct Answer is C.

Bag mass change is the dependent variable in this experiment.

In an experiment, the dependent variable is the variable that is being measured and is expected to change in response to changes in the independent variable(s).

In this case, the bag mass change is being measured and is expected to change in response to changes in the independent variable (sucrose concentration).

Choice A is incorrect because duration is not a variable in this experiment.

Choice B is incorrect because temperature is not a variable in this experiment.

Choice D is incorrect because sucrose concentration is an independent variable, not a dependent variable.

An independent variable is a variable that is manipulated by the experimenter to see how it affects the dependent


Question 3:

Which of the following indicates the function of sodium bicarbonate secreted by the pancreas?

A. Sodium bicarbonate is a protease that digests carbohydrates.

B. Sodium bicarbonate stimulates the pyloric sphincter.

C. Sodium bicarbonate inhibits peristalsis.

D. Sodium bicarbonate neutralizes the acidity of chyme.

The Correct Answer is D.

Sodium bicarbonate neutralizes the acidity of chyme.

The pancreas secretes large amounts of sodium bicarbonate, which protects the duodenum by neutralizing the acid that comes from the stomach.

This compound helps neutralize stomach acid generated during the digestive process.

 

Choice A is incorrect because sodium bicarbonate is not a protease that digests carbohydrates.

Proteases are enzymes that break down proteins, while sodium bicarbonate is a chemical compound that helps neutralize stomach acid.

Choice B is incorrect because sodium bicarbonate does not stimulate the pyloric sphincter.

The pyloric sphincter is a ring of smooth muscle that separates the stomach from the duodenum and regulates the passage of partially digested food (chyme) into the small intestine.

Choice C is incorrect because sodium bicarbonate does not inhibit peristalsis.

Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract.

 


Question 4:

Which of the following is the main function of centrosomes in animal cells?

 

A. . Organelle trafficking.

B. Pathogen digestion.

C. Cytoplasm formation

D. Microtubule organization

The Correct Answer is D.

Microtubule organization.

Centrosomes are organelles that serve as the main microtubule-organizing centers for animal cells.

They regulate the movement of microtubules and other cytoskeletal structures, thereby facilitating changes in the shapes of the membranes of animal cells.

 

Choice A, Organelle trafficking, is not the correct answer because while centrosomes do play a role in intracellular trafficking during interphase by organizing an astral ray of microtubules, their main function is microtubule organization.

Choice B, Pathogen digestion, is not the correct answer because centrosomes do not play a direct role in pathogen digestion.

Choice C, Cytoplasm formation, is not the correct answer because centrosomes do not play a direct role in cytoplasm formation.


Question 5:

Which of the following ions binds to the troponin complex, initiating contraction of a muscle?

A. Potassium.

B. Calcium.

C. Phosphorus.

D. Sodium

The Correct Answer is B.

Calcium ions play a crucial role in initiating muscle contraction.

When a muscle cell is stimulated to contract by an action potential, calcium channels open in the sarcoplasmic membrane and release calcium into the sarcoplasm.

Some of this calcium attaches to troponin, which causes it to change shape.

This shape change exposes binding sites for myosin on the actin filaments.

Myosin’s binding to actin causes crossbridge formation, and contraction of the muscle begins.

 

The other ions mentioned in the question do not have this specific role in muscle contraction.

Potassium ions are important for maintaining the resting membrane potential of cells, but they do not bind to the troponin complex.

Phosphorus ions are important for energy metabolism, but they do not bind to the troponin complex.

Sodium ions are important for generating action potentials, but they do not bind to the troponin complex.


Question 6:

In a phase diagram, which of the following is the term used for a substance held at a temperature and pressure where the solid, liquid, and gaseous states of a substance exist simultaneously?

 

 

A. Triple point

B. Critical temperature

C. Critical point

D. Absolute zero

The Correct Answer is A.

Triple point.

In a phase diagram, the term used for a substance held at a temperature and pressure where the solid, liquid, and gaseous states of a substance exist simultaneously is the triple point.

The triple point is a unique point on a phase diagram where the three states of matter (solid, liquid, and gas) can coexist in equilibrium.

At the triple point, the temperature and pressure of the substance are fixed.

Option B, critical temperature, is the temperature at which a gas cannot be liquefied, regardless of the pressure applied.

It is a characteristic property of a substance and is typically higher than the boiling point of the liquid at standard pressure.

Option C, critical point, is the point on a phase diagram where the liquid and gas phases of a substance become indistinguishable.

At the critical point, the distinction between the liquid and gas phases disappears, and the substance becomes a supercritical fluid.

Option D, absolute zero, is the theoretical temperature at which all matter has zero thermal energy.

At absolute zero, all substances are in their solid state, but it is not relevant to a phase diagram, as it is a temperature where no transitions between states occur.

In summary, the term used for a substance held at a temperature and pressure where the solid, liquid, and gaseous states of a substance exist simultaneously in a phase diagram is the triple point, whereas the other options provided are not relevant or are characteristic properties of substances in different contexts.


Question 7:

Which of the following is the number of protons in a lithium atom?

A. 7

B. 3

C. 12

D. 4

The Correct Answer is B.

The atomic number of an element represents the number of protons in the nucleus of an atom of that element.

Since lithium has an atomic number of 3, it has 3 protons in its nucleus.

 

Choice A is not correct because 7 is the mass number of lithium, not the number of protons.

Choice C is not correct because 12 is not the atomic number or mass number of lithium.

Choice D is not correct because 4 is not the atomic number or mass number of lithium.

 


Question 8:

Stimulus: 1of 1.

A group of students performed an experiment to test terminal velocity, which is the greatest speed obtained by a falling object.

The students dropped different numbers of coffee filters and measured the resulting terminal velocity.

Which of the following conclusions is supported by the data in the following data table?

#OF FILTERS

MASS (g)

TERMINAL VELOCITY (m/s)

1

1.01

1.74

2

1.99

2.48

3

3.02

3.04

4

4.0

3.50

5

5.01

3.80

 

A. Terminal velocity is when the force of gravity is equal to air resistance.

B. Heavier objects take more time to reach terminal velocity.

C. Heavier objects fall faster than lighter objects.

D. The greater the number of filters, the smaller the terminal velocity.

The Correct Answer is C.

Heavier objects fall faster than lighter objects.

The data in the table shows that as the number of filters (and therefore the mass) increases, the terminal velocity also increases.

This means that the heavier objects (with more filters) are falling faster than the lighter objects (with fewer filters).

Choice A is not supported by the data in the table as much as it is true.

Terminal velocity is indeed when the force of gravity is equal to air resistance, but this definition does not provide any information about the relationship between mass and terminal velocity.

Choice B is also not supported by the data in the table.

The data does not provide any information about the time it takes for an object to reach terminal velocity.

Choice D is not supported by the data in the table.

The data shows that as the number of filters increases, the terminal velocity also increases.

This means that the greater the number of filters, the greater (not smaller) the terminal velocity.  


Question 9:

Which of the following is correct regarding the pH scale?

A. A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4

B. A substance with a pH of 3 is two times more acidic than a substance with a pH of 4

C. A substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4

D. A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4

The Correct Answer is C.

The pH scale is a logarithmic scale that measures the acidity or alkalinity of a solution.

A solution with a pH of 7 is neutral, while a solution with a pH less than 7 is acidic and a solution with a pH greater than 7 is alkaline.

Because the pH scale is logarithmic, each whole number change in pH represents a tenfold change in acidity or alkalinity.

Therefore, a substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.

Choice A.

A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline and also incorrectly states the magnitude of the difference in acidity or alkalinity.

Choice B.

A substance with a pH of 3 is two times more acidic than a substance with a pH of 4 is not correct because it correctly states that the substance with a lower pH is more acidic but incorrectly states the magnitude of the difference in acidity.

Choice D.

A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline.


Question 10:

What is the approximate threshold value for mammalian neurons?

A. -55 mV

B. -80 mV

C. +35 mV

D. 0 mV

The Correct Answer is A.

The approximate threshold value for mammalian neurons is -55 mV.

The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.

Most often, the threshold potential is a membrane potential value between –50 and –55 mV

 

The membrane potential of a neuron is determined by the distribution of ions across the cell membrane.

At rest, the inside of a neuron is more negative than the outside due to the presence of negatively charged proteins and other molecules.

The movement of ions across the cell membrane can change the membrane potential.

For example, when sodium ions enter the cell, they make the inside of the cell more positive (less negative), causing depolarization.

Choice B is incorrect because -80 mV is below the typical threshold value for mammalian neurons.

Choice C is incorrect because +35 mV is above the typical threshold value for mammalian neurons.

Choice D is incorrect because 0 mV is above the typical threshold value for mammalian neurons.