Question

1. which membrane-bound organelle contains chromosomes and pores through which genetic material may pass?

a. the endoplasmic reticulum
b. the golgi apparatus
c. the mitochondrion
d. the nucleus

1. this model shows a type of cell. what is located at t?

cell diagram with labels u, a, r, s, t
a. the cell membrane, which is found in animal and plant cells
b. the cell membrane, which is found only in animal cells
c. the cell wall, which is found in animal and plant cells
d. the cell wall, which is found only in plant cells

1. plant cells have cell walls, while animal cells only have cell membranes surrounding them. how do these two organelles differ?

a. cell walls provide less structural support than cell membranes.
b. cell walls tend to let more small molecules through than cell membranes.
c. cell walls tend to be more rigid than cell membranes.
d. cell walls tend to be smaller than cell membranes.

Explanation:

Question 10

To solve this, we recall the function and structure of each organelle:

• Option A (Endoplasmic Reticulum): Involved in protein and lipid synthesis, no chromosomes.
• Option B (Golgi Apparatus): Modifies, sorts, and packages proteins, no chromosomes.
• Option C (Mitochondrion): Has its own DNA (mtDNA) but not in the form of chromosomes like the nucleus, and pores are not a feature.
• Option D (Nucleus): Contains the cell’s genetic material (chromosomes made of DNA and proteins) and has nuclear pores through which molecules (like RNA) can pass.

1. Identify the cell type: The model shows an animal cell (no cell wall, has centrioles).
2. Analyze "T": The structure at "T" is the cell membrane, which is present in both animal and plant cells.

• Option B: Cell membrane is not only in animal cells (plant cells have it). Eliminate.
• Option C: Cell wall is not in animal cells. Eliminate.
• Option D: Cell wall is only in plant cells, but this is an animal cell. Eliminate.

1. Recall cell wall vs. cell membrane:

• Cell Wall (Plant cells): Made of cellulose, rigid, provides structural support (maintains cell shape, protects from mechanical stress), is semi - permeable (lets small molecules through but is more rigid than cell membrane).
• Cell Membrane (Animal and Plant cells): Flexible, selectively permeable, involved in transport.

1. Analyze options:

• Option A: Cell walls provide more structural support than cell membranes (cell walls are rigid, cell membranes are flexible). Eliminate.
• Option B: Cell membranes are more selective, cell walls are more permeable to small molecules. So cell walls let more small molecules through? No, cell membranes are selectively permeable, cell walls are more like a rigid layer with pores. Actually, cell walls are more permeable, but the main difference is rigidity. Wait, let's re - evaluate:
• Option C: Cell walls (plant) are more rigid than cell membranes (both plant and animal). This is correct. Cell walls give plants their rigid structure (like in stems, leaves), while cell membranes are flexible.
• Option D: Cell walls are larger in structure (around the cell) than cell membranes (a thin layer). Size (smaller/larger) is not the main difference. Eliminate.

Answer:

D. the nucleus

Question 11

(Note: Since the cell model is an animal cell (no cell wall, has centrioles, etc.), we analyze the structure at "T":
Looking at typical animal cell structures, "T" likely represents the cell membrane (as cell wall is absent in animal cells, and other options: nucleus is "U", mitochondria are "S", etc.). But let's confirm:

• Option A: Cell membrane is in both animal and plant cells. The cell in the model is animal (no cell wall, has centrioles), so cell membrane is present.
• Option B: Cell membrane is not only in animal cells (plant cells have it too, under cell wall). Eliminate.
• Option C: Cell wall is not in animal cells. Eliminate.
• Option D: Cell wall is only in plant cells, but the model is animal cell. Eliminate.