Q: A solution has a pH of 5. What is the concentration of hydrogen ions ($$[H^+]) in $$this solution, and how does it compare to a solution with pH 7?

$$[H^+] = 1 \times 10$$^{-5}$$ \ \text{M}$$; it is 100 times more acidic than a solution with pH 7.

Q: A patient is diagnosed with a genetic disorder caused by a mutation in the DNA sequence. Which biological molecule is directly affected, and what is the central dogma describing the flow of genetic information?

Nucleic acids; $$\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$$

Question 1

Which of the following best explains why ice floats on water, and why this property is crucial for aquatic life in cold climates?

Accepted Answer

Ice is less dense than liquid water due to hydrogen bonding, which allows aquatic organisms to survive under the insulating ice layer.

Question 2

A solution has a pH of 5. What is the concentration of hydrogen ions ($$[H^+]) in $$this solution, and how does it compare to a solution with pH 7?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-5}$$ \ 	ext{M}$$; it is 100 times more acidic than a solution with pH 7.

Question 3

Which chemical group is directly involved in gene regulation and can affect whether a gene is expressed?

Accepted Answer

Methyl group ($$-CH_3$)

Question 4

A scientist observes a cell with a nucleus, mitochondria, and chloroplasts. Which type of cell is this, and what process occurs in the chloroplasts?

Accepted Answer

Plant cell; photosynthesis

Question 5

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons, while covalent bonds involve the sharing of electrons.

Question 6

Which property of water allows it to move upward through the vessels of a plant against gravity?

Accepted Answer

Cohesion and adhesion

Question 7

A patient is diagnosed with a genetic disorder caused by a mutation in the DNA sequence. Which biological molecule is directly affected, and what is the central dogma describing the flow of genetic information?

Accepted Answer

Nucleic acids; $$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$

Question 8

Which of the following statements about the cell membrane is correct?

Accepted Answer

It is composed of a phospholipid bilayer with embedded proteins that control the movement of substances.

Question 9

Which organelle is responsible for producing ATP through cellular respiration, and what is a key feature of this organelle?

Accepted Answer

Mitochondrion; contains enzymes for the electron transport chain

Question 10

A researcher observes a cell with no nucleus and no membrane-bound organelles. Which type of cell is this, and what is a likely example?

Accepted Answer

Prokaryotic cell; bacterium

Question 11

Which cytoskeletal component is primarily responsible for muscle contraction and cell movement?

Accepted Answer

Microfilaments

Question 12

Which of the following best describes the process of dehydration synthesis?

Accepted Answer

It joins monomers to form polymers by removing a molecule of water.

Question 13

Which of the following is a function of proteins in living organisms?

Accepted Answer

Enzyme catalysis, structural support, and immune defense

Question 14

A cell is observed to have a boxy shape, a large central vacuole, and chloroplasts. Which type of cell is this, and what is one structure it lacks compared to animal cells?

Accepted Answer

Plant cell; lacks lysosomes

Question 15

Which of the following best explains why phospholipids are essential for cell membrane structure?

Accepted Answer

They form a bilayer with hydrophilic heads facing outward and hydrophobic tails inward, creating a selective barrier.

Question 16

Which of the following is NOT a part of the cell theory?

Accepted Answer

All cells contain a nucleus.

Question 17

A student mixes table salt ($$	ext{NaCl}) in $$water. Which type of bond holds the sodium and chloride ions together in solid salt, and what happens to these ions in water?

Accepted Answer

Ionic bond; the ions dissociate and are surrounded by water molecules due to water's polarity.

Question 18

Which of the following best describes the role of compartmentalization in eukaryotic cells?

Accepted Answer

It allows specialized functions and separation of incompatible reactions, increasing efficiency.

Question 19

Which of the following is a correct match between a biological molecule and its function?

Accepted Answer

Glycogen – energy storage in animals

Question 20

Cilia and flagella are both involved in cell movement. What is their structural similarity?

Accepted Answer

Both are made of microtubules arranged in a 9+2 pattern.

Chemical Foundations and Cellular Structure in Biology

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