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...
20. Which of the following are characteristics of all animals?
a. multicellular, haploid cells that divide by mitosis, organisms with organ systems
b. multistage zygote development, vertebrates, reproduce sexually
c. 99 percent invertebrates, heterotrophs, multicellular
d. both A and C
D? Or just C?
23. A typical virus consists of a
a. protein coat and a cytoplasm core
b. carbohydrate coat and nucleic acid core
c. protein coat and a nucleic acid core
d. polysaccharide coat and protein core
C?
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?
Thanks
-MC
19. To determine the correct answer, let's go through each option and see if it is a general characteristic of plants:
a. Use oxygen to make usable energy: This is not a general characteristic of plants. Plants produce energy through the process of photosynthesis, where they use sunlight, water, and carbon dioxide to produce glucose and oxygen.
b. Primary producers: This is a general characteristic of plants. They are primary producers because they are capable of converting sunlight into chemical energy through photosynthesis.
c. Have specialized cells: This is a general characteristic of plants. Plants have various types of specialized cells, such as root cells, leaf cells, and stem cells, which perform different functions within the plant.
d. Cell walls composed of cellulose: This is a general characteristic of plants. Plants have cell walls made up of cellulose, which provides structural support and protection to the cells.
Based on this analysis, option a. "use oxygen to make usable energy" is NOT a general characteristic of plants. Therefore, the answer is a.
20. Let's evaluate each option to determine the correct characteristics of all animals:
a. Multicellular, haploid cells that divide by mitosis, organisms with organ systems: This is not a correct characteristic. Animals are usually diploid, meaning they possess two sets of chromosomes (except for certain exceptions like haplodiploid organisms). Also, haploid cells typically divide by meiosis, not mitosis. Lastly, while many animals have organ systems, not all of them do.
b. Multistage zygote development, vertebrates, reproduce sexually: This is not a correct characteristic either. While most animals do reproduce sexually, not all of them follow a multistage zygote development, and not all animals are vertebrates.
c. 99 percent invertebrates, heterotrophs, multicellular: This is a correct characteristic. Almost all animals are multicellular, are heterotrophs (meaning they obtain nutrients from other organisms), and the majority (about 99%) of animals are invertebrates.
d. Both A and C: This option cannot be the correct answer since option C already includes option A.
Based on this analysis, option c. "99 percent invertebrates, heterotrophs, multicellular" is the correct answer.
23. Let's examine the options to identify the correct composition of a typical virus:
a. Protein coat and a cytoplasm core: This is not accurate. Viruses do not possess cytoplasm, which is a substance found within cells.
b. Carbohydrate coat and nucleic acid core: This is not accurate either. While some viruses may have a carbohydrate coat (called a glycocalyx), it is not a general characteristic. However, viruses do have a nucleic acid core, which contains their genetic material.
c. Protein coat and a nucleic acid core: This is the correct answer. Viruses have a protein coat called a capsid, which contains their nucleic acid core, either DNA or RNA.
d. Polysaccharide coat and protein core: This option is not accurate. Viruses do not typically possess a polysaccharide coat.
Based on this analysis, option c. "protein coat and a nucleic acid core" is the correct answer.
24. Let's assess each option to identify what happens when the HIV virus attaches to CD4 receptors on a macrophage:
a. Attaches to a CCR5 receptor before it's able to enter the cell: This is the correct answer. After attaching to the CD4 receptor on a macrophage, the HIV virus usually attaches to a co-receptor called CCR5 before it can enter the cell.
b. Enters the cell through the CD4 receptors: This option is not accurate. While the HIV virus initially attaches to CD4 receptors, it does not directly enter the cell through them.
c. Attaches to a lymphocyte that attempts to fight the virus on the macrophage: This option is not accurate. Lymphocytes are usually targeted by the HIV virus, but their interaction with macrophages is different from what is described here.
d. HIV tricks the reverse transcriptase of the infected cell into making copies of the viral RNA molecule: This option describes a later stage of the HIV replication cycle but does not specifically address the attachment of the virus to CD4 receptors on macrophages.
Based on this analysis, option a. "attaches to a CCR5 receptor before it's able to enter the cell" is the correct answer.
I hope this explanation helps! Let me know if you have any further questions.