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 option (b) "lack organization into tissues and organs but have specialized cells." Sponges are multicellular organisms that lack true tissues and organs. Instead, they have specialized cells that perform different functions, such as capturing food and removing waste.
To arrive at this answer, let's analyze the options:
a. Option (a) states that sponges are nonsymmetrical and have oscula. Oscula are large openings through which water exits the sponge. While sponges can be nonsymmetrical and have oscula, this alone doesn't define their organization or lack thereof, so we can eliminate this option.
b. Option (b) correctly states that sponges lack organization into tissues and organs but have specialized cells. This is true and identifies one of the key characteristics of sponges.
c. Option (c) suggests that sponges possess cells capable of recognizing other sponge cells and have a simple digestive system. While sponges do have specialized cells, the recognition of other sponge cells is not a defining characteristic, and their digestive system is more rudimentary than simple. Thus, this option can be disregarded.
d. Option (d) combines both options (a) and (b). As already analyzed, option (a) alone is not accurate, and option (b) accurately characterizes sponges. Therefore, we can conclude that option (d) is not the correct answer.
To summarize, the correct answer is option (b): sponges lack organization into tissues and organs but have specialized cells.
Moving on to the next questions:
7. The correct answer for question 7 is option (a) "pseudocoelomate body plan." Mollusks are characterized by a true coelom, which is a fluid-filled body cavity completely lined with mesoderm. They do not have a pseudocoelomate body plan, which is a characteristic of some other animal groups.
Let's evaluate the options:
a. Option (a) correctly identifies that pseudocoelomate body plan does not apply to mollusks. Mollusks have a true coelom, as mentioned before.
b. Option (b) states that mollusks have bilateral symmetry. Bilateral symmetry is indeed a characteristic of mollusks, so it cannot be the answer.
c. Option (c) indicates that mollusks have a complete digestive tract, which is correct. Mollusks possess a mouth and an anus, allowing for unidirectional food processing.
d. Option (d) describes a heavy fold that forms the outer body layer, which is not a characteristic unique to mollusks. Therefore, this option can be discarded.
Hence, the correct answer is option (a): pseudocoelomate body plan, which is not a characteristic of mollusks.
8. The correct answer for question 8 is option (a) "have true coeloms." Both mollusks and annelids do have true coeloms, which are fluid-filled body cavities lined with mesoderm.
Let's assess the other options:
a. Option (a) accurately states that mollusks and annelids have true coeloms, so it cannot be the answer.
b. Option (b) claims that both mollusks and annelids have closed circulatory systems, which is partially correct. Some mollusks, like cephalopods, have closed circulatory systems, but not all mollusks do. Annelids, on the other hand, generally have closed circulatory systems. As this statement is not entirely true for mollusks, we can eliminate this option.
c. Option (c) suggests that both mollusks and annelids have well-developed respiratory systems. While this is generally true for annelids, mollusks have a wide range of respiratory adaptations. Some have gills, others have lungs, and some even use their skin for respiration. Therefore, this option is not entirely accurate for mollusks.
d. Option (d) states that both mollusks and annelids carry out asexual reproduction. This option is incorrect because both groups are capable of both sexual and asexual reproduction. Therefore, option (d) can be eliminated.
In conclusion, the correct answer is option (a): mollusks and annelids have true coeloms.
I hope this helps clarify the answers for you. If you have any further questions, feel free to ask!