Question

1. why is the cell membrane said to be \selectively permeable\? since some \stuff\ can come out and some must stay out the cell membrane is said to be selectively permeable 2. what are the three molecules the cell membrane is primarily made of? 1 lipids 2. proteins 3. carbohydrates 3. what is the role of each molecule in the cell membrane? 1. lipids- forms main part of the membrane around the cell 2. proteins- 3. carbohydrates- 4. define passive transport 5. what are 3 types of passive transport? 6. describe the three types of passive transport. 1. diffusion- 2. osmosis- 3 facilitated diffusion 7. what does it mean to \move down the concentration gradient\? 8. what types of molecules can diffuse through the cell membrane, without using a channel protein? 9. why is it so important for your body to maintain water or sugar homeostasis?

Explanation:

1. The cell - membrane is selectively permeable because it allows certain substances to pass through while restricting others, based on factors like size, charge, and solubility.
2. The three main molecules are lipids (form the bilayer), proteins (involved in transport, signaling etc.), and carbohydrates (for cell - cell recognition).
3. Proteins can act as transporters, receptors, enzymes etc. in the cell membrane. Carbohydrates are often attached to lipids or proteins and are involved in cell - cell recognition and adhesion.
4. Passive transport is the movement of substances across the cell membrane without the use of energy (ATP).
5. The three types are diffusion (movement of solutes from high to low concentration), osmosis (movement of water from high to low water - potential), and facilitated diffusion (movement of substances with the help of transport proteins down their concentration gradient).
6. Diffusion is the random movement of molecules from an area of higher concentration to an area of lower concentration. Osmosis is the diffusion of water across a semi - permeable membrane. Facilitated diffusion uses membrane proteins (channel or carrier proteins) to move substances across the membrane.
7. Moving down the concentration gradient means moving from an area of higher concentration of a substance to an area of lower concentration.
8. Small, non - polar molecules like oxygen and carbon dioxide can diffuse through the cell membrane without using a channel protein.
9. Maintaining water or sugar homeostasis is crucial for proper cell function. Imbalances can lead to cell swelling or shrinking (in case of water), and improper functioning of metabolic pathways (in case of sugar).

Answer:

1. It allows certain substances to pass while restricting others.
2. Lipids, Proteins, Carbohydrates
3. Proteins: transporters, receptors etc.; Carbohydrates: cell - cell recognition
4. Movement of substances across the cell membrane without using energy.
5. Diffusion, Osmosis, Facilitated Diffusion
6. Diffusion: random movement of solutes from high to low concentration; Osmosis: diffusion of water; Facilitated Diffusion: movement with transport proteins down concentration gradient
7. Moving from an area of higher substance concentration to lower concentration.
8. Small, non - polar molecules (e.g., oxygen, carbon dioxide)
9. For proper cell function; imbalances can cause cell damage and metabolic issues.