Question

problem set 3: choose one of the problems below to complete. problem a: water is needed inside and outside of all cells of the body to help with transport of molecules. our bodies work to maintain a balance of nutrients inside and outside the cells. when someone is dehydrated, they do not have enough water outside the cells causing the environment outside the cells to have a higher concentration of nutrients than inside the cell. if a person is dehydrated, what will happen to the water in their cells if the nutrients cannot pass through the cell membrane? what will happen to the size of the cell? problem b: plants need water do photosynthesis and to maintain turgor pressure. this is where the large vacuole of the plant has enough water in it to push against the cell wall and helps keep it rigid. the plant uses this water in photosynthesis to produce energy and can release water through transpiration when it is hot. in houston, summer typically has sunny, hot days and you notice that your plants are wilting. you water the plant to help it. explain what will happen on a cellular level after you have watered the plant. what will happen to the turgor pressure in the plant? which did you choose? problem a or problem b (circle one) 1. type of cellular transport: ____________ energy required? __________ 2. concentration gradient explanation: __________ 3. claim, evidence, reasoning (cer) claim: __________ evidence: __________ reasoning (model with explanation): ____________

Explanation:

Problem A

1. Type of cellular transport: Osmosis. Osmosis is the movement of water across a semi - permeable membrane from an area of lower solute concentration to an area of higher solute concentration. In dehydration, water moves out of the cell due to the higher solute concentration outside the cell. Energy is not required as it is a passive process.
2. Concentration Gradient Explanation: When a person is dehydrated, the extracellular environment has a higher concentration of solutes (such as salts and nutrients) compared to the inside of the cell. Water will move out of the cell following the concentration gradient of water (from higher water concentration inside the cell to lower water concentration outside the cell).
3. Claim, Evidence, Reasoning (CER):

• Claim: The water in the cells will move out and the size of the cell will decrease.
• Evidence: Dehydration causes an imbalance in solute concentration with more solutes outside the cell.
• Reasoning: According to the principles of osmosis, water moves from an area of lower solute concentration (inside the cell) to an area of higher solute concentration (outside the cell) when the nutrients cannot pass through the cell membrane to balance the concentration. As water leaves the cell, the cell shrinks in size.

Problem B

1. Type of cellular transport: Osmosis. When water is added to the wilting plant, water enters the plant cells' large vacuoles through osmosis. This is a passive process and no energy is required.
2. Concentration Gradient Explanation: After watering the plant, the extracellular environment (surrounding the plant cells) has a higher water concentration compared to the inside of the plant cells (especially the vacuoles) which were low on water due to wilting. Water moves into the cells down its concentration gradient.
3. Claim, Evidence, Reasoning (CER):

• Claim: After watering the plant, water will enter the plant cells and the turgor pressure will increase.
• Evidence: Wilting plants have low water in their vacuoles and adding water changes the water concentration outside the cells.
• Reasoning: Osmosis causes water to move into the plant cells' vacuoles. As the vacuole fills with water, it pushes against the cell wall, increasing the turgor pressure. This restores the rigidity of the plant and helps it stand upright again.

Answer:

Problem A

1. Type of cellular transport: Osmosis, Energy Required? No
2. Concentration Gradient Explanation: Higher solute concentration outside the cell in dehydration causes water to move out of the cell following the water concentration gradient.
3. Claim: The water in the cells will move out and the size of the cell will decrease. Evidence: Dehydration causes an extracellular - higher solute concentration. Reasoning: Osmosis makes water move from lower solute (higher water) concentration inside the cell to higher solute (lower water) concentration outside when nutrient - transport is blocked.

Problem B

1. Type of cellular transport: Osmosis, Energy Required? No
2. Concentration Gradient Explanation: After watering, higher water concentration outside the plant cells causes water to move into the cells.
3. Claim: After watering the plant, water will enter the plant cells and the turgor pressure will increase. Evidence: Wilting plants have low water in vacuoles and watering changes the external water concentration. Reasoning: Osmosis causes water to enter vacuoles, increasing turgor pressure as it pushes against the cell wall.