Cellular Structure and Function Flashcards

A student observes a cell under a microscope and notes the presence of a cell wall, ribosomes, and a circular loop of DNA not enclosed in a nucleus. Which of the following is the most likely classification for this cell?

Answer: A prokaryotic cell

The defining characteristics described—a cell wall, ribosomes, and genetic material not contained within a nucleus—are all hallmarks of a prokaryotic cell, such as a bacterium. Plant and fungal cells are eukaryotic and have a nucleus, and animal cells lack a cell wall.

A new drug is developed that specifically targets and disables the mitochondria within a cell. What essential cellular process would be most directly inhibited by this drug?

Answer: Cellular respiration

Mitochondria are known as the 'powerhouses' of the cell because they are the primary site of cellular respiration. This process converts glucose and oxygen into ATP (adenosine triphosphate), the main energy currency for most cellular functions. Disabling mitochondria would halt this energy production.

In multicellular organisms, cells differentiate to perform specific jobs. Which statement best explains how different cell types, like muscle cells and nerve cells, develop from a single fertilized egg?

Answer: Different genes are activated or expressed in each cell type.

All somatic cells in an organism generally contain the same full set of genes (genome). Cell differentiation occurs because specific genes are 'turned on' (expressed) or 'turned off' in different cells, leading to the production of specific proteins that determine the cell's unique structure and function.

A scientist is studying the hierarchical organization of a complex mammal. Which of the following lists correctly represents a level of organization from simplest to most complex?

Answer: Cell -> Tissue -> Organ -> Organ system

The correct biological hierarchy starts with the basic unit of life, the cell. Groups of similar cells form tissues. Different tissues work together to form an organ. Finally, multiple organs collaborate as an organ system to perform major functions for the organism.

A person engages in strenuous exercise, causing their body temperature to rise. In response, they begin to sweat, which cools the body as it evaporates. This scenario is an example of a cell or organism maintaining what state?

Answer: Homeostasis

Homeostasis is the process by which living organisms maintain a stable internal environment despite changes in external conditions. The body's response of sweating to cool down is a classic example of a negative feedback loop used to maintain a constant internal temperature.

Which of the following correctly describes the function of the cell membrane?

Answer: It controls the passage of substances into and out of the cell.

The cell membrane is a selectively permeable barrier that encloses the cell. Its primary function is to regulate which molecules, such as nutrients, ions, and waste products, can enter or leave the cytoplasm, thereby maintaining the cell's internal environment.