1. Sponges
a. are nonsymmetrical and have oscula
b. lack organization into tissues and organs but have specialized cells
c. possess cells that are capable of recognizing other sponge cells and have a simple digestive system
d. both a and b
I'm so confused on this question, because I think it's all of them...?
7. Which of the following is NOT a characteristic of mollusks?
a. pseudocoelomate body plan
b. bilateral symmetry
c. complete digestive tract
d. heavy fold that forms the outer body layer
A?
8. Both mollusks and annelids
a. have true coeloms
b. have closed circulatory systems
c. have well-developed respiratory systems
d. carry out asexual reproduction
A?
Thanks
-MC
1. The correct answer for the first question is d. both a and b. Sponges are organisms that lack organization into tissues and organs, but they have specialized cells. They are also nonsymmetrical and have oscula to allow water to flow through them.
Regarding how to arrive at the answer, you can break down the options one by one:
a. Sponges are indeed nonsymmetrical, meaning they do not have a symmetrical body plan. They also have oscula, which are large openings that allow water to exit the sponge.
b. This option suggests that sponges lack organization into tissues and organs but have specialized cells. This is correct because sponges do not have specialized tissues or organs like other animals, but they do have specialized cells to perform specific functions.
c. This option states that sponges possess cells capable of recognizing other sponge cells and have a simple digestive system. While sponges do have specialized cells, they do not have a complex digestive system. Instead, they rely on intracellular digestion, which occurs within individual cells.
Therefore, the correct answer is d. both a and b.
Moving on to the second question:
7. The correct answer is a. pseudocoelomate body plan. Mollusks do not have a pseudocoelomate body plan. Instead, they have a true coelom, which is a fluid-filled body cavity completely lined with mesoderm.
To determine the correct answer, let's analyze the options:
a. A pseudocoelomate body plan refers to organisms that have a body cavity that is not entirely lined with mesodermal tissue. Mollusks, however, have a true coelom, which is completely lined with mesoderm.
b. Bilateral symmetry is a characteristic shared by many organisms, including mollusks. This is not the correct answer.
c. Mollusks do have a complete digestive tract. This means they have a mouth and an anus, allowing for a unidirectional flow of food.
d. This option refers to a heavy fold that forms the outer body layer, which is not a characteristic of mollusks.
Therefore, the correct answer is a. pseudocoelomate body plan.
Moving on to the third question:
8. The correct answer is b. have closed circulatory systems. Both mollusks and annelids generally have an open circulatory system, in which the blood or hemolymph flows freely through the body cavity.
To determine the correct answer, let's review the options:
a. Both mollusks and annelids have true coeloms. This means they have a fluid-filled body cavity completely lined with mesodermal tissue.
b. This option states that both mollusks and annelids have closed circulatory systems. However, mollusks typically have an open circulatory system, whereas annelids generally have closed circulatory systems.
c. Mollusks, including organisms like snails and clams, have well-developed respiratory systems, such as gills or lungs. Annelids, like earthworms, also have well-developed respiratory systems, typically through their moist skin.
d. Asexual reproduction refers to the production of offspring without the involvement of gametes (e.g., sperm and eggs). While some mollusks and annelids can engage in asexual reproduction through methods like fragmentation or budding, it is not a characteristic common to both groups.
Therefore, the correct answer is b. have closed circulatory systems.