Biology SOL Unit 2 Test - Cell Transport

What is the chemical composition of a water molecule?

• Two hydrogen atoms and one oxygen atom

• One hydrogen atom and two oxygen atoms

• Two oxygen atoms and one nitrogen atom

• One hydrogen atom and one carbon atom

Answer explanation

A water molecule consists of two hydrogen atoms bonded to one oxygen atom, represented as H2O. This is the correct chemical composition, making the first answer choice accurate.

Tags

NGSS.HS-ESS2-5

Categorize the following accordingly.

Groups:

(a) Capillary Action

,

(b) Adhesion

,

(c) Surface Tension

,

(d) Cohesion

• Water droplets stick to leaves.

• Water molecules to stick to each other.

• Water molecules stick tightly together so that insects can walk on it without sinking.

• Water molecules to stick to other substances.

•  Fluid flows through a narrow tube or space from surface tension, cohesion, and adhesion.

• It does not require energy to occur.

Answer explanation

Refer to your notes after the test before retaking it.

Tags

NGSS.HS-ESS2-5

Match the following percentages with the approximate amount of water in the human body.

• Percentage of water in human muscles

• 30-40%

• Percentage of water in human bones

• 60-70%

• Percentage of water in the whole human body

• 80-90%

• Percentage of water in the human eye

• 10-20%

Answer explanation

Refer to your notes after the test before retaking it.

Why is water considered a polar molecule?

• It has equal sharing of electrons between atoms.

• The oxygen atom is slightly negative and the hydrogen atoms are slightly positive.

• It contains only hydrogen atoms.

• It is a non-covalent compound.

Answer explanation

Water is a polar molecule because the oxygen atom has a higher electronegativity, making it slightly negative, while the hydrogen atoms become slightly positive. This unequal sharing of electrons creates a dipole moment.

Explain how the polarity of water molecules contributes to both cohesion and adhesion.

• The polarity causes water molecules to repel each other, leading to cohesion and adhesion.

• The polarity allows water molecules to form hydrogen bonds with each other (cohesion) and with other substances (adhesion).

• The polarity makes water molecules non-reactive, preventing cohesion and adhesion.

• The polarity increases the temperature of water, causing cohesion and adhesion.

Answer explanation

The polarity of water molecules allows them to form hydrogen bonds, which leads to cohesion (water molecules attracting each other) and adhesion (water molecules attracting other substances). This is crucial for many biological and physical processes.

Which of the following best describes a homogeneous mixture?

• A mixture where you can distinguish the solute and solvent easily.

• A mixture that does not mix at all.

• A mixture with a uniform composition throughout.

• A mixture that contains only one substance.

Answer explanation

A homogeneous mixture has a uniform composition throughout, meaning its components are evenly distributed and not easily distinguishable. This distinguishes it from heterogeneous mixtures, where differences are visible.

Which statement is true about a solvent?

• It is always a solid.

• It is a substance that is dissolved in another substance.

• It dissolves other substances.

• It cannot dissolve chemicals or minerals.

Answer explanation

The correct statement is that a solvent dissolves other substances. It is not always a solid, nor is it the substance being dissolved. Solvents can dissolve various chemicals and minerals.

Which of the following is the best example of a solute that can dissolve completely in water to form a solution?

• Water

• Sugar

• Oil

• Butter

Answer explanation

Sugar is a solute that dissolves completely in water, forming a homogeneous solution. In contrast, water is a solvent, while oil and butter do not dissolve in water, making sugar the best example.

What is homeostasis?

• The process by which two substances of mix uniformly

• The process by which a living organism maintains a stable internal environment

• The process of dissolving solutes in solvents

• The process of heating substances to high temperatures

Answer explanation

Homeostasis is the process by which a living organism maintains a stable internal environment, ensuring optimal conditions for survival despite external changes. This distinguishes it from the other options provided.

Tags

NGSS.HS-LS1-3

(a)   is the movement of water from an area of high concentration of water molecules to an area of low concentration to reach isotonicity (equilibrium).​ (b)   is the process by which a higher concentration of air particles moves to an area with a lower concentration, while​ ​ (c)   is the movement of molecules across a membrane with the help of transport proteins, still following the concentration gradient.

• Active Transport

• Osmosis

• Diffusion

• Facilitated Diffusion

• Cohesion

Answer explanation

Osmosis refers to water movement from high to low concentration, while diffusion describes the movement of air particles similarly. Facilitated diffusion involves transport proteins aiding molecule movement along the concentration gradient.