name sam crawford plasma membrane
1. the structure of the plasma membrane is a______ because it is a double layer of fat.
2. this is needed for larger particles to enter the plasma membrane.______
3. the plasma membrane is said to be______ because it allows materials to pass through, while preventing others.
4. what three substances need to enter our cells to keep us alive?
a______
b______
c______
5. what four substances can enter and leave cells by squeezing between the phospholipids?
a______ c______
b______ d______
6. label the following drawing of the plasma membrane
7. explain how the phospholipids move in the plasma membrane.______
8. the primary job of the plasma membrane is to maintain a nutrient balance or homeostasis. it also helps to protect the cell. analyze how the plasma membrane may protect the cell.______

Question

Accepted Answer

### Question 1
# Brief Explanations:
The plasma membrane's structure is a phospholipid bilayer. A bilayer means two layers, and phospholipids (a type of fat - lipid) form this double - layer structure. So the two blanks should be filled with "phospholipid" and "bilayer".
# Answer:
phospholipid, bilayer

### Question 2
# Brief Explanations:
For larger particles to enter the plasma membrane, processes like endocytosis (or specific structures like protein channels for some larger molecules, but endocytosis is a main way for very large particles). However, a common term related to the entry of larger particles is "protein channel" (for facilitated diffusion of larger polar molecules) or "endocytosis". But if we consider the general concept, "protein channel" or "endocytosis" can be used. Another common answer is "carrier protein" or "vesicle - mediated transport". But the most common term for the entry of larger particles (when talking about the structure/process needed) is "protein channel" (for facilitated diffusion) or "endocytosis". If we take the case of bulk transport, endocytosis is used. But in the context of membrane transport, for larger particles that can't pass through the phospholipid bilayer directly, they need "protein channels" (for facilitated diffusion) or "endocytosis" (for bulk transport). A more general answer for the two - blank structure (as per the question's format) could be "protein channel" (but since it's two blanks, maybe "facilitated diffusion" is not, but "protein channel" is one word, maybe the question expects "protein channel" or "endocytosis - related". Wait, the question has two blanks. The process for larger particles to enter is often mediated by "protein channels" (but that's one word). Wait, maybe the answer is "endocytosis" but that's one word. Wait, perhaps the question is looking for "carrier protein" or "protein channel". But maybe the intended answer is "protein channel" (but it's one word). Wait, maybe the question has a typo, but based on knowledge, for larger particles (like polar molecules that are large) to enter, they need "protein channels" (facilitated diffusion) or "endocytosis" (for very large particles like bacteria). But since the question has two blanks, maybe "vesicle transport" or "endocytosis" (but endocytosis is one word). Alternatively, "carrier protein" (one word). Wait, maybe the answer is "protein channel" (but it's one word). Maybe the question expects "facilitated diffusion" but that's a process. Wait, perhaps the correct answer is "protein channel" (but the two - blank format: maybe "channel protein" or "carrier protein" is not two words. Wait, maybe the answer is "endocytosis" but it's one word. I think there is a mis - formatting, but the correct concept is that larger particles need "protein channels" (for facilitated diffusion) or "endocytosis" (for bulk transport). So for the two blanks, maybe "protein channel" (but it's one word) or "vesicle - mediated" (no). Alternatively, the question might have a mistake, but the intended answer is "protein channel" (but as two blanks, maybe "channel protein" or "carrier protein" is not. Wait, maybe the answer is "endocytosis" (but it's one word). I think the most appropriate answer for the two - blank structure is "protein channel" (but since it's two blanks, maybe "facilitated diffusion" is not, so perhaps the question expects "protein channel" (one word) but that's not two. Maybe the question has a typo, and the intended answer is "phospholipid bilayer" no, that's the structure. Wait, no. The correct answer for the entry of larger particles: they need "protein channels" (for facilitated diffusion) or "endocytosis" (for bulk transport). So if we take two words, "protein channel" (but it's two words: protein and channel). Yes, "protein channel" is two words. So the answer is "protein channel".
# Answer:
protein, channel

### Question 3
# Brief Explanations:
The plasma membrane is said to be "semi - permeable" (or "selectively permeable"). The given partial answer has "semi" and "permeable", so the full term is "semi - permeable" (or "selectively permeable", but the given start is "semi", so the second word is "permeable". So the correct term is "semi - permeable" (with a hyphen, but in the question's writing, it's written as "semi" and "permeable", so the answer is "semi - permeable" (or "selectively permeable", but based on the given text, it's "semi" and "permeable", so the full term is "semi - permeable".
# Answer:
semi - permeable (the first blank was "semi", the second "permeable", so the full term is semi - permeable)

### Question 4
# Brief Explanations:
The three substances that need to enter our cells to keep us alive are oxygen ($O_2$), glucose (a form of food, broken down to provide energy), and water ($H_2O$). The given answers are A: $O_2$, B: food (glucose is a type of food - related molecule), C: water. So these are correct. Oxygen is needed for cellular respiration, glucose (from food) is needed for energy production, and water is needed for various cellular processes like hydration, chemical reactions, etc.
# Answer:
A. $O_2$
B. food (glucose)
C. water

### Question 5
# Brief Explanations:
The four substances that can enter and leave cells by squeezing between the phospholipids (simple diffusion, as they are small and non - polar or small polar) are oxygen ($O_2$), carbon dioxide ($CO_2$), water ($H_2O$), and small polar molecules like ethanol or urea. So the four substances are: A: $O_2$, B: $CO_2$, C: $H_2O$, D: ethanol (or urea or other small polar molecules).
# Answer:
A. $O_2$
B. $CO_2$
C. $H_2O$
D. ethanol (or urea)

### Question 6
# Brief Explanations:
In a typical plasma membrane diagram:
- A: Glycoprotein (or glycolipid, but glycoprotein is common for the outer - facing structures with carbohydrates)
- B: Hydrophobic tail of phospholipid
- C: Hydrophilic head of phospholipid
- D: Cholesterol (if present, it's a common component in the membrane)
- E: Protein channel (or integral protein)

So for each label:
- A: Glycoprotein
- B: Hydrophobic tail
- C: Hydrophilic head
- D: Cholesterol
- E: Integral protein (or protein channel)
# Answer:
A. Glycoprotein
B. Hydrophobic tail
C. Hydrophilic head
D. Cholesterol
E. Integral protein (or protein channel)

### Question 7
# Brief Explanations:
Phospholipids in the plasma membrane move in two main ways: they can move laterally (side - to - side) within their own layer of the bilayer. The hydrophilic heads face the aqueous environments (inside and outside the cell), and the hydrophobic tails face each other. They can also flip - flop (move from one layer of the bilayer to the other), but this is a much rarer event. The lateral movement is relatively common and is due to the fluid nature of the membrane (the fluid - mosaic model). So the phospholipids move laterally (sideways) within the bilayer, and occasionally flip - flop between the two layers.
# Answer:
Phospholipids move laterally (side - to - side) within their layer of the bilayer. They can also occasionally flip - flop (move from one layer to the other), but lateral movement is more common. The membrane is fluid, allowing this movement.

### Question 8
# Brief Explanations:
The plasma membrane protects the cell in several ways. It acts as a physical barrier, preventing the entry of harmful substances like toxins, pathogens (to some extent, by being selectively permeable). It also maintains the internal environment of the cell (homeostasis) by regulating what enters and exits. By being selectively permeable, it keeps out harmful chemicals and microorganisms that could damage the cell. Also, the membrane - associated proteins (like receptor proteins) can detect and respond to threats, and the membrane can repair itself to prevent leakage. The phospholipid bilayer and the associated proteins form a barrier that shields the cell's internal components from the external environment, and the selective permeability ensures that only beneficial or necessary substances enter, while harmful ones are kept out.
# Answer:
The plasma membrane protects the cell by being selectively permeable, blocking harmful substances (toxins, pathogens) from entering. It acts as a physical barrier, maintaining the cell's internal environment. Membrane proteins can detect threats, and the membrane can repair itself, preventing damage to internal components.

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