Question 5 1 pts You are performing an experiment to measure how respiratory rat

Question

Question 5 1 pts You are performing an experiment to measure how respiratory rate changes in response to increasing intensity of aerobic exercise. Which of the following would be the independent variable? age of subjects sex of subjects intensity of exercise respiratory rate Several of these are correct Question 6 1 pts Which of the following is most likely to pass through the phospholipid bilayer of the cell membrane without a transporter? glucose (a carbohydrate) a steroid hormone (derived from lipids) hemoglobin (a protein) lactate dehydrogenase (an enzyme)

Explanation / Answer

A steroid hormone can pass the phospholipid bilayer of the cell membrane along their concentration gradient as they are lipid-soluble molecules. It's a passive diffusion process, no energy is involved.

The phospholipids are arranged in a bilayer, with their polar, hydrophilic phosphate heads facing outwards, and their non-polar, hydrophobic fatty acid tails facing each other in the middle of the bilayer. This hydrophobic layer acts as a barrier. Small and nonpolar (hydrophobic) molecules can freely pass through the membrane, but charged ions and large molecules such as proteins and sugars are barred passage. It only allows the lipid soluble, or very small molecules, to pass through it.

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