Lesson 4 Cells Review

Which of the following is included in cell theory?

• Living organisms are composed of two or more cells.

• All cells reproduce by sexual reproduction.

• Cells form spontaneously in the proper environment.

• Cells pass hereditary material during cell division.

Answer explanation

Although many living organisms are multicellular and reproduce sexually, these characteristics are not common to all living organisms. The cell theory states that all living organisms are composed of ONE or more cells, cells are the basic unit of structure and function of living organisms, all cells arise from pre-existing cells by division, and cells pass hereditary material from parent to offspring cells during cell division.

All cells contain cytoplasm, _____.

• a plasma membrane, ribosomes, genetic information, and RNA

• a cell wall, ribosomes, and genetic information

• a plasma membrane, a nucleus, and ribosomes

• a plasma membrane, a cell wall, ribosomes, genetic information, and RNA

Answer explanation

The cytoplasm of all cells is surrounded by a protective plasma membrane, but cell walls are not present in all living organisms. Human cells, for example, are not covered by cell walls. All cells contain genetic information that produces RNA, proteins, and ribosomes made of RNA and proteins. However, only eukaryotic cells protect their genetic information (DNA) inside a nucleus

In which of these cell types would you expect to find a cell wall?

• most animal and plant cells

• most plant and prokaryotic cells

• most animal and prokaryotic cells

• most animal, plant, and prokaryotic cells

Answer explanation

A cell wall provides protection and structural support in many unicellular organisms such as bacteria and archaeans. However, a cell wall is also rigid and forces the cell to maintain a single shape. Unicellular or multicellular organisms that move by altering cell shape are not surrounded by a rigid cell wall. For example, a cell wall would prevent the contracting and relaxing of muscle cells that move many animals. Because plants are non-motile, cells walls are able to provide structural support and protection to plant cells.

Which of this best differentiates a prokaryotic cell from a eukaryotic cell?

• Prokaryotic cells are much larger than eukaryotic cells.

• Prokaryotic cells have flagella, but eukaryotic cells do not.

• Prokaryotic cells have cell walls, but eukaryotic cells do not.

• Prokaryotic cells lack a membrane-bound nucleus.

Answer explanation

Prokaryotic cells do not contain membrane-bound organelles. Therefore, hereditary material is stored in the cytoplasm, where all metabolic processes are performed.

Which of the following statements concerning prokaryotes is true?

• Bacteria are more closely related to eukaryotes than to archaeans.

• Prokaryotes contain DNA and ribosomes.

• Prokaryotic flagella are composed of microtubules and motor proteins.

• All prokaryotes belong to the same taxonomic domain.

Answer explanation

Two of the three taxonomic domains are comprised of prokaryotic organisms, Archaea and Bacteria. Biochemical and genetic comparisons indicate that archaeans are more closely related to eukaryotes than to bacteria. Despite significant differences, all living organisms contain hereditary material in the form of DNA and ribosomes that use the information contained in each cell’s DNA to produce proteins.

In eukaryotic cells, chromosomes containing genetic information essential to life are found in the _____.

• nucleus

• rough endoplasmic reticulum

• Golgi complex

• mitochondria

Answer explanation

Hereditary material is stored in the nucleus as chromosomes, DNA condensed and organized by proteins. The nuclear membrane provides protection for these molecules.

The nuclear envelope provides protection primarily with its _____.

• double phospholipid bilayer containing regulated membrane pores

• single phospholipid bilayer containing regulated membrane pores

• double phospholipid bilayer containing open membrane pores

• single phospholipid bilayer containing open membrane pores

Answer explanation

The double phospholipid bilayer nuclear membrane blocks entry and exit of biomolecules into the nucleus. Large nuclear pores are formed by transmembrane proteins that allow tightly regulated passage of specific molecules.

Vesicles are _____.

• large storage centers

• small, membrane-bound spheres

• organelles that lack a membrane

• major energy producers of the cell

Answer explanation

Vesicles are small, membrane-bound organelles that transport fluid and biomolecules within the cell.

What is the sequence of protein transport from inside to outside the cell?

• rough endoplasmic reticulum, transport vesicle, Golgi complex, secretory vesicle, plasma membrane

• smooth endoplasmic reticulum, secretory vesicle, rough endoplasmic reticulum, Golgi complex, transport vesicle, plasma membrane

• Golgi complex, transport vesicle, rough endoplasmic reticulum, secretory vesicle, plasma membrane

• smooth endoplasmic reticulum, transport vesicle, Golgi complex, secretory vesicle, plasma membrane

Answer explanation

Rough endoplasmic reticulum is covered with ribosomes that secrete proteins into the lumen of the endoplasmic reticulum. Transport vesicles take proteins to the Golgi complex for modification. Secretory vesicles then transport the final product to the plasma membrane. The vesicle binds with the plasma membrane, and the vesicular contents are released outside the cell.

A steroid hormone would most likely be synthesized by the _____.

• nucleus

• rough endoplasmic reticulum

• smooth endoplasmic reticulum

• Golgi complex

Answer explanation

The function of the smooth endoplasmic reticulum varies depending on cell type, but is commonly associated with lipid synthesis, including steroid hormones and fatty acids.