19. Which is NOT a general characteristic of plants?

a. use oxygen to make usable energy
b. primary producers
c. have specialized cells
d. cell walls composed of cellulose
I think it might be either A or B...

24. During initial HIV infection, the HIV virus attaches to CD4 receptors on a macrophage and then
a. attaches to a CCR5 receptor before it's able to enter the cell
b. enters the cell through the CD4 receptors
c. attaches to a lymphocyte that attempts to fight the virus on the macrophage.
d. HIV tricks the reverse transcriptase of the infected cell into making copies of the viral RNA molecule.
A?

-MC

a, a are the best choices. Both are not good choices, but I wont go into that.

...yes I will...
Plants do use oxygen to make usable energy (from glucose, in the process of respiration)especially at night, but the other three choices are worse.
HIV is of two strains, X4 and R5. For R5, a) is the correct answer. For the X4 strain, there is no correct answer. X4 uses the co-recptor CXCR4 to get into the cell.
...

So A for both of them?

-MC

MC --

a, a are the best choices

Right, sorry.

-MC

To answer the first question, we need to determine which of the given characteristics is NOT true for plants. Let's analyze each option:

a. Plants do not use oxygen to make usable energy. They undergo the process of photosynthesis, where they use carbon dioxide, water, and sunlight to produce glucose and release oxygen as a byproduct.

b. Primary producers are organisms that convert energy from sunlight through photosynthesis, which is true for plants. So, this is a general characteristic of plants.

c. Plants have specialized cells that perform specific functions like photosynthesis, nutrient absorption, and structural support. This is also a general characteristic of plants.

d. Cell walls composed of cellulose are a defining characteristic of plant cells. Cellulose provides rigidity and support to plant cell walls. This is another general characteristic of plants.

By evaluating the options, we can conclude that option a. (use oxygen to make usable energy) is the one that is NOT a general characteristic of plants. Therefore, option a. is the correct answer.

For the second question about HIV infection, let's analyze each option:

a. After attaching to a macrophage's CD4 receptor, the HIV virus also attaches to a CCR5 receptor before it can enter the cell. This is correct.

b. HIV enters the cell through the CD4 receptors on the macrophage. This is incorrect because after attaching to the CD4 receptors, HIV needs to attach to a CCR5 co-receptor before entering the cell.

c. HIV does not attach to a lymphocyte during the initial infection. It primarily targets and infects CD4+ T cells, damaging the host's immune system over time.

d. HIV does trick the reverse transcriptase enzyme of the infected cell into making copies of the viral RNA molecule, enabling the virus to replicate within the host cell. This is correct.

By evaluating the options, we can conclude that option b. is incorrect, and the correct answer is option a. (HIV attaches to a CCR5 receptor before entering the cell). So, option a. is the correct answer to the second question.