Water (H2O), carbon dioxide (CO2), and oxygen (O2) are all quite small molecules, yet they move across cell membranes differently. Both CO2 and O2 passively diffuse across the cell membrane directly while H2O moves across the cell membrane by facilitated diffusion. What can be concluded about these three molecules based on the way they react to the cell membrane? (4 points)
A) The water molecules are attracted to the lipid tails of the cell membrane, but the carbon dioxide and oxygen molecules are not.
B) The water molecules are too small to pass between the lipid tails of the cell membrane, while the molecules of carbon dioxide and oxygen are not.
C) The water molecules are repelled by the lipid tails of the cell membrane, but the carbon dioxide and oxygen molecules are not.
D) The water molecules are too large to pass between the lipid tails of the cell membrane, while the molecules of carbon dioxide and oxygen are not.
Answers
Answer:
Multi-cellular organism’s like humans have very big body and require a lot of oxygen to diffuse into body quickly in order to meet the oxygen requirement. Diffusion is a slow process which will take a lot of time to circulate oxygen to all the body cells. Because of its slow nature diffusion is insufficient to meet the oxygen requirements of multicellular organisms like humans.
2. What criteria do we use to decide whether something is alive?
Solution:
Walking, breathing, growth and other visible changes can be used to determine whether something is alive or dead. However some living things will have changes that are not visible to our eye; Hence, presence of life process is a fundamental criteria to decide whether something is alive.
3. What are outside raw materials used for by an organism?
Solution:
Outside raw material is used by organism for food and oxygen. Raw materials requirement varies on the complexity of the organism and the environment it is living.