Question

cell membranes are made up of.
a phospholipids.
b phosphates.
c potassium.
d phosphorus.
e proteins.

question 30
atoms are made up of.
a positively charged protons, negatively charged neutrons, and neutral electrons.
b positively charged electrons, negatively charged neutrons, and neutral protons.
c positively charged protons, negatively charged electrons, and neutral neutrons.
d negatively charged protons, positively charged electrons, and neutral neutrons.
e positively charged neutrons, negatively charged electrons, and neutral neutrons.

Explanation:

Question about Cell Membranes:

Cell membranes are primarily composed of a phospholipid bilayer, along with proteins (integral and peripheral). Option A (phospholipids) is a main component, and option E (proteins) is also a component. But the question asks "are made up of" and the most fundamental structural component is phospholipids. However, if considering the options, both A and E are correct in parts, but the standard primary component is phospholipids. Wait, actually, cell membranes are made of a phospholipid bilayer (so A) and proteins (E). But maybe the question has a typo or expects the main lipid component. Wait, the options: A is phospholipids, E is proteins. Both are components. But let's check: the cell membrane structure is phospholipid bilayer with embedded proteins. So if the question is "made up of" and the options, maybe the intended answer is A (phospholipids) as the main structural lipid, or E? Wait, no—phospholipids form the bilayer, which is the basic structure. Proteins are also part of the membrane. But maybe the question is from a basic biology context where phospholipids are the main component. Alternatively, maybe the question has a mistake, but among the options, A (phospholipids) and E (proteins) are both components. Wait, let's recheck: cell membranes are composed of phospholipids (forming the bilayer), proteins (for transport, structure, etc.), cholesterol (in animal cells), and carbohydrates. So among the options, A (phospholipids) and E (proteins) are correct. But maybe the question expects A? Or maybe E? Wait, no—phospholipids are the primary structural component. So the answer for the first question (cell membranes) is A. phospholipids and E. proteins? But the options are single choice? Wait, the original question: "Cell membranes are made up of." The options are A to E. Let's recall: the fluid mosaic model states that the cell membrane is a mosaic of phospholipids, cholesterol, proteins, and carbohydrates. So phospholipids (A) and proteins (E) are both components. But maybe the question is designed to have A as the answer (since the bilayer is made of phospholipids), or E? Wait, no—phospholipids are the main lipid component. So the correct answer is A. phospholipids (and also E, but maybe the question considers A as the primary).

Atoms are composed of a nucleus (containing protons, which are positively charged, and neutrons, which are neutral) and electrons (negatively charged) orbiting the nucleus. So the correct description is positively charged protons, negatively charged electrons, and neutral neutrons. This matches option C.

Answer:

A. phospholipids, E. proteins (Note: In some contexts, both are correct, but if single choice, A is more about the lipid bilayer structure. However, proteins are also a major component. Maybe the question has a mistake, but based on options, A is a key component.)

Question about Atoms: