Homeostasis: Feedback Loops!
Name the 2 types of feedback loops. Explain them individually in detail.
Negative and positive!
Negative F.L: Counteracts the initial effect, reducing the effect of a change to stabilize it.
Positive F.L: Increases more of a reaction. The change grows.
What are the 3 main functions of the cell membrane?
1. Acts as a barrier
2. Controls what comes in and out of the cell
3. Allows for cell communication
25 glucose molecules inside cell ----> 5 glucose molecules outside cell
Arrow indicates movement
Diffusion. High to low concentration.
Name the function of the digestive system.
Breaks down food into smaller, simpler nutrients that can be absorbed into the bloodstream.
What does anaerobic respiration produce instead of Co2 as a byproduct that causes cramps during intense exercise?
Lactic Acid
Define homeostasis and what happens when homeostasis is not achieved. Be as detailed as possible!
A process in which organisms maintain stability, also known as EQUILIBRIUM while adjusting to optimal conditions.
When a cell reaches equilibrium, what does that mean?
A state in which the movement of molecules into a cell is balanced by the movement of molecules out of the cell, creating a stable internal environment. E.g. 50% molecules inside, 50% molecules outside.
Compare and contrast diffusion and osmosis.
Diffusion is the movement of molecules from high concentration to low concentration, moving all solute molecules except for H2O molecules.
Osmosis is the movement of molecules from high concentration to low concentration, but only H2O molecules.
How does the raw materials for cellular respiration reach everywhere in the body?
Circulatory system.
What is the cell membrane composed of?
Phospholipid bi-layer.
Scenario: When a person climbs to a high altitude, the body detects lower oxygen levels and starts producing more red blood cells to carry oxygen. Is this a positive or negative feedback loop?
Negative feedback loop. The system works to counteract the change (low oxygen) and bring the body back to a stable state.
Name 2 traits of active transport. (Something only active transport has.)
Any of the following mentioned is correct:
Requires ATP
Low to high concentration
Going against the concentration gradient
State one reason for the color change in the model cell at it's final state. (E.g. cell turning black, water turning orange)
Iodine diffused through the cell. The cell being black means that the iodine was able to go through the cell membrane and detect the starch inside, turning black.
Similarly, the color turning orange indicates there is a presence of glucose in the water, meaning that the glucose diffused out of the cell into the water.
Where does the raw exchange of materials take place in the human body?
Capillaries.
Some molecules can diffuse and some are unable to diffuse across the cell membrane. Beside the cell membrane's semi-permeable layer, name another reason why certain molecules may pass or not pass.
Bonus 50 points: Give me 2 reasons.
Large molecules cannot pass the cell membrane as easily, while smaller molecules can.
Bonus: Polar molecules cannot pass as easily as nonpolar molecules.
Scenario: When your body experiences a severe drop in blood oxygen levels, cells start to die, releasing signals that cause further tissue damage and oxygen depletion. Is this a positive or negative feedback loop?
Positive feedback loop. This process amplifies the problem, as the oxygen levels drop further.
Name 2 passive transport traits. (What does passive transport have that active does not?)
Any of the following mentioned is correct:
Does not require ATP
High to low concentration
Going with concentration gradient
What are the two molecules that can diffuse across the cell membrane?
Bonus 50 points: explain why.
Iodine and glucose
Both are small molecules that can easily pass through the semi-permeable membrane.
Explain how the increased pulse rate as a result of exercising helps the body maintain homeostasis.
The heart/pulse rate increases because the heart is trying to bring the necessary nutrients to the whole body, pumping blood faster. More oxygen means more energy.
Name 2 types of active transport.
Exocytosis - active removal of molecules out of the cell.
Endocytosis - a cell actively taking something in.
Scenario: When blood sugar levels drop too low, the pancreas releases the hormone glucagon, which signals the liver to release stored glucose into the bloodstream. As glucose levels rise, the pancreas stops releasing glucagon. Is this a positive or negative feedback loop?
Negative feedback loop. The system is working to restore balance by increasing the low blood sugar until there is regular amounts of blood sugar.
Why are some molecules able to diffuse and others are unable to diffuse across the cell membrane?
The cell membrane is semi-permeable, only some molecules can pass easily while others can not.
What is one molecule that cannot diffuse across the cell membrane?
Bonus 50 points: explain why.
Starch.
It is a large molecule that cannot pass through the cell membrane as easily. The iodine did not turn the water black meaning the starch was not in the water, only in the cell.
Explain how exercise affects the rate of cellular respiration. Talk about: Co2 production, breathing rate, and heart rate.
Exercise increases the rate of cellular respiration. The demand for energy increases. The breathing rate increases because the body needs more oxygen and expells Co2, the heart rate increases to bring the oxygen to other parts of the body, and the Co2 production increases as it is a byproduct of cellular respiration and there is more oxygen to exchange in the lungs.
Name all 3 types of passive transport.
FOR DOUBLE POINTS: explain all 3 of them and the differences.
Simple diffusion, facilitated diffusion, and osmosis.
Double points: Simple diffusion is transport without protein assistance. Facilitated diffusion is movement with the help of transport proteins. Osmosis is transport of H2O molecules only.