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📝 Cell theory and cell as basic unit of life (7 MCQs)

📖 From Campbell Biology • 1. Evolution and the theme of Biology and Scientific Inquiry • 7 questions available

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What is Cell theory and cell as basic unit of life?

Definition:
Cell theory establishes that all living organisms are composed of one or more cells, the cell is the basic structural and functional unit of life, and new cells arise from existing cells. These principles provide a foundation for understanding living organisms.

Working:
Cells carry out essential life processes such as obtaining energy, responding to stimuli, maintaining internal conditions, and reproducing.

Example:
A bacterium consists of a single cell that performs all necessary life functions, while a human contains many specialized cells working together.

Reason:
Cells are considered the basic units of life because every organism depends on cellular activities to survive, grow, reproduce, and maintain organization.

Easy

Medium

Hard

📝 All Cell theory and cell as basic unit of life MCQs

Q1. A researcher isolates a structure from a multicellular organism and finds that it cannot independently perform energy processing, maintain an internal boundary, or reproduce. Which conclusion best supports the idea that cells are fundamental units of life?

A.The isolated structure must be an organ because it cannot reproduce

B.The structure lacks the coordinated organization required for an independent cellular unit ✅

C.All structures smaller than tissues are necessarily nonliving

D.Only structures containing genetic material can be considered parts of organisms

💡 Difficulty: medium | ✅ Correct: B

📖 Explanation: A cell is characterized by coordinated structural and functional organization that allows it to maintain internal conditions, process energy and information, and reproduce or contribute to reproduction. A smaller isolated structure may perform one function but does not independently represent the basic living unit.

Q2. Two organisms have similar organs, but microscopic analysis shows that one organism's tissues contain cells with very different internal structures from those of the other organism. Which inference is most scientifically justified?

A.Different cellular structures can produce differences in how tissues perform their functions ✅

B.Organ-level similarities prove that the cells must have identical structures

C.Cellular structure has little influence on tissue-level function

D.Tissues determine cellular organization but never depend on it

💡 Difficulty: medium | ✅ Correct: A

📖 Explanation: Cells form the structural foundation of tissues and organs, so differences in cellular organization can lead to differences in function. Similarity at a larger organizational level does not require identical cellular structures or mechanisms.

Q3. A drug blocks a membrane protein responsible for transporting a nutrient into cells. After treatment, cellular nutrient levels fall and energy production decreases. Which explanation best connects the observations?

A.The drug directly destroys the organism's organs

B.Reduced transport can limit cellular resources needed for metabolic processes ✅

C.The membrane protein normally produces all cellular energy

D.Lower nutrient levels prove that cells do not regulate their internal environment

💡 Difficulty: hard | ✅ Correct: B

📖 Explanation: The observations form a logical sequence: blocking the membrane transport protein reduces nutrient entry, lower intracellular nutrient availability can restrict metabolic pathways, and reduced metabolism can decrease energy production. This demonstrates how a cellular structure can directly influence cellular function.

Q4. A student argues, \Because an organ can perform a function that an individual cell cannot perform alone, the organ must be the basic unit of life.\" What is the main flaw in this reasoning?"

A.The student assumes that organs are always smaller than cells

B.The student ignores that organs are built from interacting cells whose coordinated activities produce organ functions ✅

C.The student assumes that all cells perform exactly the same function

D.The student confuses genetic information with cellular structure

💡 Difficulty: hard | ✅ Correct: B

📖 Explanation: The argument overlooks biological organization. Organs can perform complex functions because many specialized cells interact in an organized way. The fact that an organ has emergent capabilities does not replace the cell as the fundamental structural and functional unit.

Q5. A graph shows the percentage of cells remaining metabolically active after exposure to increasing concentrations of a chemical: 0 units: 100%, 2 units: 92%, 4 units: 75%, 6 units: 48%, and 8 units: 15%. Which interpretation best connects the graph to cellular organization?

A.Increasing chemical concentration appears to disrupt cellular functions, reducing the proportion of active cells ✅

B.The graph proves that the chemical affects only organs and not cells

C.The decline shows that cells become larger as chemical concentration increases

D.The graph demonstrates that all cells respond identically at every concentration

💡 Difficulty: hard | ✅ Correct: A

📖 Explanation: The decreasing percentage of metabolically active cells indicates that increasing chemical concentration is associated with impaired cellular function or survival. Because metabolism occurs at the cellular level, the pattern supports investigating cellular structures or processes as possible targets.

Q6. A tissue contains two cell types. Type X has abundant structures associated with energy processing, while Type Y has fewer of them but many structures specialized for producing and exporting proteins. A researcher observes that Type X cells consume more oxygen, whereas Type Y releases more protein. Which conclusion is best supported?

A.Cellular structures are unrelated to specialized functions

B.Different cell types can develop structural features that match their particular functional demands ✅

C.Type Y must be less metabolically active because it releases proteins

D.Type X cannot contribute to tissue-level function because it specializes in energy processing

💡 Difficulty: hard | ✅ Correct: B

📖 Explanation: The observations connect structure with function at the cellular level. Type X's greater abundance of energy-processing structures is consistent with higher oxygen consumption, while Type Y's specialized protein-producing and exporting machinery supports its secretory role. Cellular specialization therefore contributes to tissue function.

Q7. A scientist compares a single-celled organism with a cell isolated from a multicellular organism. Both can obtain nutrients and exchange materials with their surroundings, but only the single-celled organism continues normal growth and reproduction after isolation. Which explanation best integrates these observations?

A.Every isolated cell must function independently because all cells are complete organisms

B.The single-celled organism performs all essential life processes within one cellular system, whereas the isolated multicellular cell may depend on interactions with other cells ✅

C.The multicellular cell cannot exchange materials because it lacks a cell boundary

D.Reproduction is unrelated to cellular organization and therefore cannot distinguish the two cases

💡 Difficulty: hard | ✅ Correct: B

📖 Explanation: The comparison highlights two levels of biological organization. A single-celled organism contains the structures and coordinated processes needed for independent life, whereas a specialized cell from a multicellular organism may require signals, nutrients, or support from neighboring cells. Thus, cellular structure and interactions determine functional independence.

🔗 Related Topics (MCQs)

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