If an atom has one valence electron, which of the following characteristics will it exhibit when reacting with other elements?

Meiosis is the cellular process that produces gametes (sex cells) such as sperm in males and eggs (ova) in females.

Key features of meiosis:

• It occurs in reproductive organs (gonads) — the testes and ovaries.
• It involves two rounds of cell division: Meiosis I and Meiosis II.
• It produces four haploid daughter cells, each with half the number of chromosomes of the original cell.

Humans normally have 46 chromosomes (diploid, 2n) in body cells.
Meiosis produces gametes with 23 chromosomes (haploid, n) so that when fertilization occurs, the embryo returns to 46 chromosomes.

Why the Other Options Are Incorrect

Apoptosis

• Programmed cell death used to remove damaged or unnecessary cells.
• Does not produce new cells or gametes.

Glycogenesis

• A metabolic process where glucose is converted into glycogen for storage in the liver and muscles.
• Related to energy storage, not cell reproduction.

Mitosis

• Produces two identical diploid cells.
• Used for growth, tissue repair, and cell replacement.
• Does not produce gametes.

Key Takeaway Points

• Meiosis produces gametes (sex cells).
• Gametes are haploid (23 chromosomes in humans).
• Meiosis involves two divisions → Meiosis I and Meiosis II.
• It creates genetic variation through:
  • Crossing over
  • Independent assortment

Quick TEAS Memory Tip

• Meiosis = Making eggs & sperm
• Mitosis = Making body cells

To understand this question, we need to understand passive immunity and how it differs from active immunity.

1. What Is Passive Immunity?

Passive immunity occurs when a person receives antibodies from another source instead of producing them themselves.

In passive immunity:

• The body does not create its own antibodies
• Antibodies are transferred from another individual
• Protection occurs immediately
• The immunity is temporary because the body does not form memory cells

2. Example of Passive Immunity

One of the most common natural examples of passive immunity occurs between a mother and her baby.

Antibodies are transferred in two main ways:

During pregnancy

Maternal antibodies (IgG) cross the placenta to protect the fetus.

After birth

Antibodies (IgA) are transferred through breast milk.

These antibodies help protect the baby from infections while the baby's immune system is still developing.

3. Why the Correct Answer Is Passive Immunity

The option:

“A mother passes antibodies to her child through breast milk.”

is passive immunity because:

• The baby receives antibodies directly
• The baby did not produce the antibodies itself
• The protection is temporary

Why the Other Options Are Incorrect

Immunization leads to the activation of B-cell proliferation.

This describes active immunity, where the body produces its own antibodies after vaccination.

After primary exposure to an antigen, memory T cells remain to respond to a secondary exposure.

This describes immune memory, which is part of active immunity, not passive immunity.

Exposure to a virus leads to the production of antibodies that can bind to the virus.

This also describes active immunity, because the body is producing its own antibodies.

Key Takeaway Points

Passive immunity = receiving antibodies

Antibodies come from another person or source.

Passive immunity provides immediate protection

Protection begins right away because antibodies are already present.

Passive immunity is temporary

Because the body does not create memory cells, the protection does not last long.

Common examples of passive immunity

TEAS Exam Memory Trick

Think of this phrase:

Passive = Passing antibodies

If antibodies are given to you, it is passive immunity.

If your body makes the antibodies, it is active immunity.

To solve this question, determine each subatomic particle one at a time:

1. Number of protons

The atomic number equals the number of protons.

• Atomic number = 15
• So, the atom has 15 protons

2. Number of neutrons

The mass number equals:

protons + neutrons

So:

31 = 15 + neutrons

Neutrons = 31 - 15 = 16

So, the atom has 16 neutrons.

3. Number of electrons

A neutral atom has the same number of protons and electrons.

• Neutral atom with atomic number 15 has 15 electrons

But the question says the atom is an anion with a negative 3 charge.

An anion is negatively charged because it has gained electrons.

• Negative 3 charge means it gained 3 extra electrons

So:

15 + 3 = 18 electrons

That gives:

• 15 protons
• 16 neutrons
• 18 electrons

So the correct answer is C.

Why the Other Choices Are Incorrect

A. 15 protons, 16 neutrons, 15 electrons

This would describe the neutral atom, not the 3- anion.

B. 15 protons, 16 neutrons, 12 electrons

This would mean the atom lost 3 electrons, giving it a 3+ charge, not a 3- charge.

C. 15 protons, 16 neutrons, 18 electrons

This is correct because a 3- charge means the atom has 3 more electrons than protons.

D. 12 protons, 31 neutrons, 15 electrons

This does not match the atomic number or the mass number relationships given in the question.

Key Concept

Use these rules for atom questions:

• Atomic number = protons
• Mass number = protons + neutrons
• Neutral atom: protons = electrons
• Negative charge: gained electrons
• Positive charge: lost electrons

A quick memory trick:

• Anion = added electrons
• Cation = electrons carried away

Take Away Points

• Atomic number tells you the number of protons.
• Subtract atomic number from mass number to find neutrons.
• A 3- charge means the atom gained 3 electrons.
• Protons do not change when an atom becomes an ion.
• Neutrons also do not change when charge changes.

This question involves phase changes and gas pressure.

The key concept here is sublimation, which is when a substance changes directly from a solid to a gas without passing through the liquid phase.

Dry ice is the solid form of carbon dioxide (CO₂). When dry ice sublimates, it turns directly into CO₂ gas.

1. What Happens When Dry Ice Sublimates?

When dry ice changes from solid CO₂ to gaseous CO₂:

• Solid CO₂ molecules become free-moving gas molecules
• The gas molecules spread out and occupy more space
• The number of gas particles in the container increases

Because the container is sealed, the gas cannot escape.

2. Why Pressure Increases

Pressure in a gas occurs when gas molecules collide with the walls of a container.

As dry ice sublimates:

1. More CO₂ gas molecules are produced.
2. These gas molecules move freely throughout the container.
3. They collide with the container walls more frequently.

More collisions with the container walls result in greater pressure.

So the best explanation is that gas CO₂ particles occupy more space, leading to increased pressure.

3. Gas Behavior vs Solid Behavior

When CO₂ changes from solid → gas, the particles become much farther apart and mobile, which increases pressure inside a sealed container.

Why the Other Options Are Incorrect

Gas CO₂ molecules move faster when CO₂ is a solid.

Molecules in a solid move much less than gas molecules. Gas molecules move faster because they have greater freedom of movement.

CO₂ molecules combine to form larger molecules in the gas phase.

CO₂ molecules do not combine during sublimation. They remain individual CO₂ molecules.

CO₂ particles exert less force on the container walls as a gas.

Gas particles actually exert more force because they collide with the container walls frequently.

Key Takeaway Points

Sublimation

Sublimation is the change of state from:

Solid → Gas

Example: Dry ice (solid CO₂) → CO₂ gas

Gas pressure

Gas pressure is caused by collisions of gas particles with container walls.

More particles = more collisions = higher pressure

Gas particles spread out

Gas molecules move freely and occupy more space than solid particles.

Sealed containers trap gases

If gas forms inside a sealed container, the pressure will increase because the gas cannot escape.

TEAS Exam Memory Trick

Remember:

More gas particles → More collisions → Higher pressure

This question tests your understanding of enzyme activity and factors that affect enzyme reaction rates.

The enzyme catalase speeds up the breakdown of hydrogen peroxide (H₂O₂) into:

This reaction produces water and oxygen gas.

Enzymes like catalase act as biological catalysts, meaning they increase the rate of chemical reactions.

Several factors influence enzyme activity, including:

• temperature
• pH
• enzyme concentration
• substrate concentration
• inhibitors

In this question, the key factor is temperature.

Effect of Temperature on Enzymes

Increasing temperature (within a reasonable range) causes molecules to:

• move faster
• collide more frequently
• form enzyme–substrate complexes more often

This leads to an increased reaction rate.

Therefore, placing the beaker in a warm water bath increases the reaction rate.

However, temperatures that are too high can denature enzymes and stop the reaction.

But moderate warming generally speeds up enzyme activity.

Why the Other Options Are Incorrect

Add a noncompetitive inhibitor

A noncompetitive inhibitor binds to a site on the enzyme other than the active site.

This causes:

• a change in enzyme shape
• reduced enzyme activity

Therefore, it decreases the reaction rate, not increases it.

Add ice cubes to the reaction beaker

Lower temperatures cause molecules to:

• move more slowly
• collide less frequently

This slows enzyme activity.

So adding ice would decrease the reaction rate.

Add a competitive inhibitor

A competitive inhibitor competes with the substrate (hydrogen peroxide) for the enzyme’s active site.

This reduces the number of successful enzyme–substrate interactions.

Thus, the reaction rate decreases.

Catalase Example

Catalase is often used in experiments because it rapidly breaks down hydrogen peroxide.

Signs the reaction is occurring include:

• bubbling or foaming
• oxygen gas release

The faster the bubbles appear, the faster the reaction rate.

Key Takeaway Points

Enzymes speed up chemical reactions

Enzymes lower the activation energy needed for reactions.

Temperature affects enzyme activity

Moderate increases in temperature:

• increase molecular movement
• increase collision frequency
• increase reaction rate

Very high temperatures can denature enzymes.

Inhibitors slow enzyme reactions

Two main types:

• Competitive inhibitors → block the active site
• Noncompetitive inhibitors → change enzyme shape

Both reduce reaction rate.

Cold temperatures slow enzyme activity

Low temperature reduces:

• molecular movement
• enzyme-substrate interactions

TEAS Exam Memory Trick

Think:

Warm = faster enzymes

Cold = slower enzymes

And:

Inhibitors = slower reactions

This question tests your understanding of gene expression and protein synthesis inside the cell.

The key statement in the question is:

“The cell is able to make copies of its genetic information but is unable to produce encoded proteins.”

This tells us that:

• DNA replication is working
• But protein synthesis is not occurring

The cellular structure responsible for protein synthesis is the ribosome.

1. How Genetic Information Becomes Protein

Cells use a process called gene expression to convert genetic information into proteins.

This occurs in two major steps:

Step 1: Transcription

DNA → mRNA

• Occurs in the nucleus
• The DNA code is copied into messenger RNA (mRNA)

The question states the cell can make copies of its genetic information, meaning this step is working.

Step 2: Translation

mRNA → Protein

• Occurs at the ribosome
• Ribosomes read the mRNA instructions and build proteins from amino acids

If the cell cannot produce proteins, the issue is likely with the ribosomes, where translation occurs.

2. What Ribosomes Do

Ribosomes are the cellular structures responsible for protein synthesis.

Their function is to:

• Read mRNA instructions
• Assemble amino acids
• Build polypeptide chains (proteins)

Ribosomes can be found:

• Floating freely in the cytoplasm
• Attached to the rough endoplasmic reticulum (RER)

Without ribosomes, the cell cannot produce proteins, even if DNA and mRNA are present.

Why the Other Options Are Incorrect

Acrosome

The acrosome is a structure found in sperm cells that contains enzymes used to penetrate the egg during fertilization.

It has nothing to do with protein production in general cells.

Centrosome

The centrosome organizes microtubules and helps form the mitotic spindle during cell division.

It is involved in cell division, not protein synthesis.

Golgi Apparatus

The Golgi apparatus modifies, sorts, and packages proteins after they are made.

It does not produce proteins.

If ribosomes fail, proteins never reach the Golgi.

Key Takeaway Points

Ribosomes make proteins

Protein synthesis occurs during translation at ribosomes.

DNA → RNA → Protein

This process is called the central dogma of molecular biology.

If proteins cannot be produced, suspect ribosomes

Even if DNA replication and transcription work normally, protein synthesis cannot occur without ribosomes.

Ribosomes are found in two locations

• Free ribosomes → make proteins used inside the cell
• Rough ER ribosomes → make proteins for export or membranes

TEAS Exam Memory Trick

Think of ribosomes as protein factories.

If a question mentions:

• Protein production
• Translation
• mRNA being converted to protein

➡ The answer is usually ribosomes.

This question tests knowledge of the female urinary system and the functions of its structures.

The urethra is the tube that carries urine from the urinary bladder to the outside of the body.

After urine is produced by the kidneys and stored in the bladder, it must exit the body through a passageway. This passageway is the urethra.

Urinary pathway in the body

The flow of urine follows this sequence:

1. Kidneys – filter blood and produce urine
2. Ureters – transport urine from the kidneys to the bladder
3. Bladder – stores urine temporarily
4. Urethra – carries urine from the bladder to the outside of the body

Therefore, the structure that connects the bladder to the outside is the urethra.

Female Urethra

In females, the urethra is:

• about 3–4 cm long
• shorter than the male urethra
• located anterior to the vagina

Because it is shorter, bacteria can reach the bladder more easily, which is why urinary tract infections (UTIs) are more common in females.

Why the Other Options Are Incorrect

Vagina

The vagina is part of the female reproductive system, not the urinary system.

Functions:

• receives sperm during sexual intercourse
• acts as the birth canal
• allows menstrual flow to leave the body

It does not carry urine from the bladder.

Fallopian tubes

Fallopian tubes are part of the female reproductive system.

Their function is to:

• transport eggs from the ovaries to the uterus
• provide the site where fertilization typically occurs

They have no role in urine transport.

Ureter

The ureters transport urine from the kidneys to the bladder.

They do not connect the bladder to the outside of the body.

Key Takeaway Points

Urine leaves the body through the urethra

The urethra connects the bladder to the outside.

Urinary system pathway

The flow of urine is:

Kidneys → Ureters → Bladder → Urethra

Ureters vs Urethra

Students often confuse these.

Female urethra is shorter

This increases the risk of urinary tract infections (UTIs).

TEAS Exam Memory Trick

Remember:

Ureter → Up to bladder
Urethra → Out of body

The correct answer is B. Venn diagram because the question asks for a graph that can show overlap between different organisms.

That phrase is the biggest clue in the question.

A Venn diagram is specifically designed to show:

• relationships among groups
• shared characteristics
• areas of overlap between categories

In this case, the information describes animal classification groups and how different organisms belong to broader biological categories. A Venn diagram is the best choice when the goal is to visually represent how groups relate and where they may share common traits or connections.

Why a Venn Diagram Fits Best

The passage discusses:

• Bilateria
• two major superphyla:
  • protostomes
  • deuterostomes
• examples of organisms within each group

When a reader needs to understand how categories connect or compare, a Venn diagram is useful because it can visually organize:

• what belongs to one group
• what belongs to another group
• what traits or characteristics may be shared

Even in a general newspaper article, a Venn diagram can simplify complex biological classification by showing relationships in a visually easy format.

Why the Other Choices Are Incorrect

A. Histogram

A histogram is used to show the distribution of numerical data, usually grouped into intervals.
It is not used to show relationships or overlap among biological groups.

B. Venn diagram

This is correct because Venn diagrams are ideal for showing overlap and shared features among categories.

C. Pie chart

A pie chart shows parts of a whole as percentages or proportions.
It does not effectively show overlap between groups.

D. Scatter plot

A scatter plot is used to show the relationship between two numerical variables.
It is not appropriate for showing category overlap in classification groups.

Key Concept

This question is testing your ability to choose the correct type of graph based on the information being presented.

A quick guide:

• Venn diagram = overlap/shared traits between groups
• Pie chart = parts of a whole
• Histogram = frequency distribution of numerical data
• Scatter plot = relationship between two numerical variables

Because the question specifically says show overlap, the best answer is immediately Venn diagram.

This question is testing your understanding of molarity.

1. What is molarity?

Molarity (M) is defined as:

A solution that is 1 M contains:

• 1 mole of solute
• in 1 liter of solution

So the correct choice must give exactly 1 mole per 1 liter.

2. Check each answer choice

Option 1: 53.6 g of NH₄Cl in 1 L of water

Given:

• Molar mass of NH₄Cl = 53.6 g/mol

Step 1: Find moles

Step 2: Divide by volume

This is exactly 1 M.

Option 2: 58.4 g of NaCl in 100 L of water

Given:

• Molar mass of NaCl = 58.4 g/mol
  (The image says g/mL, but for molarity this should be interpreted as g/mol.)

Step 1: Find moles

Step 2: Divide by volume

Not 1 M.

Option 3: 100 g of CaCO₃ in 10 L of water

Given:

• Molar mass of CaCO₃ = 100 g/mol
  (Again, the image likely intended g/mol.)

Step 1: Find moles

Step 2: Divide by volume

Not 1 M.

Option 4: 180 g of C₆H₁₂O₆ in 0.1 L of water

Given:

• Molar mass of C₆H₁₂O₆ = 180 g/mol

Step 1: Find moles

Step 2: Divide by volume

Not 1 M.

Why the first option is correct

The first option has exactly:

• 1 mole of NH₄Cl
• in 1 liter

That matches the definition of 1 molar (1 M) exactly.

Key Takeaway Points

Molarity formula

Always use this formula for molarity questions.

To find moles

You usually calculate moles first, then molarity.

A 1 M solution means

• 1 mole
• per 1 liter

Watch the volume carefully

Most wrong answers in molarity questions happen because the amount of solute is 1 mole, but the volume is not 1 liter.

Examples:

• 1 mole in 10 L = 0.1 M
• 1 mole in 100 L = 0.01 M
• 1 mole in 0.1 L = 10 M

TEAS Exam Memory Trick

Think:

Molarity = Moles Over Liters

M = mol / L

If you see a mass and molar mass:

1. Convert to moles
2. Divide by liters

This question tests your understanding of pH, hydrogen ion concentration (H⁺), and hydroxide ion concentration (OH⁻).

The pH scale measures how acidic or basic a solution is.

Where:

• H+= hydrogen ion concentration.

1. Determine the Hydrogen Ion Concentration

If the pH = 10, we can determine the hydrogen ion concentration:

So the hydrogen ion concentration is:

2. Relationship Between H⁺ and OH⁻

Water maintains a constant relationship:

So if:

Then:

Thus, the hydroxide ion concentration is 10⁻⁴.

This matches the correct answer.

3. Why the Other Answers Are Incorrect

The solution is a weak acid.

A solution with pH = 10 is basic, not acidic.

Acids have pH less than 7.

The solution is neutral.

Neutral solutions have:

A pH of 10 is basic.

The solution has a hydrogen ion concentration of 10⁻⁴.

If hydrogen ion concentration were 10⁻⁴, then:

That would be acidic, not basic.

Understanding the pH Scale

Examples:

Since pH 10 is above 7, it is a basic solution.

Key Takeaway Points

1️⃣ pH measures hydrogen ion concentration

Higher pH = lower hydrogen ion concentration.

2️⃣ H⁺ and OH⁻ are inversely related

If hydrogen decreases, hydroxide increases.

3️⃣ Basic solutions have higher OH⁻

At pH 10:

• low H⁺
• high OH⁻

4️⃣ Each pH unit is a 10× change

For example:

• pH 9 → 10× more basic than pH 8
• pH 10 → 100× more basic than pH 8

TEAS Exam Memory Trick

Think:

pH + pOH = 14

For pH 10: