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 to question 1 is option (b). Sponges lack organization into tissues and organs but have specialized cells. To arrive at this answer, let's break down the options:
a. Sponges are indeed nonsymmetrical and have oscula (large openings for water outflow), but this option does not mention anything about the organization of tissues and organs.
b. This option correctly describes sponges. They do not possess distinct tissues or organs like other organisms but do have specialized cells for various functions.
c. While sponges possess specialized cells, they do not have a simple digestive system that recognizes other sponge cells. They have a simple feeding system that functions at the cellular level.
Therefore, the answer is option (b), as it accurately describes the characteristics of sponges.
7. The correct answer to question 7 is option (a). Pseudocoelomate body plan is not a characteristic of mollusks. To determine this, let's analyze the options:
a. Pseudocoelomate body plan refers to having a false coelom, which is a fluid-filled body cavity not completely lined with mesoderm. Mollusks do not have a pseudocoelomate body plan.
b. Mollusks do exhibit bilateral symmetry, with their body being divisible into two mirror-image halves along a central plane.
c. Mollusks possess a complete digestive tract, meaning they have a mouth and anus, allowing for unidirectional flow of food through their digestive system.
d. The heavy fold that forms the outer body layer is known as a mantle, which is a characteristic feature of mollusks. Therefore, it is not the correct option to choose.
Hence, the answer is option (a), as pseudocoelomate body plan is not a characteristic of mollusks.
8. The correct answer to question 8 is option (a). Both mollusks and annelids have true coeloms. Let's consider the options:
a. True coelom refers to having a fluid-filled body cavity completely lined with mesoderm. Both mollusks and annelids possess true coeloms.
b. While both mollusks and annelids have circulatory systems, not all of them have closed circulatory systems. Some mollusks have an open circulatory system, where the blood is not entirely enclosed within vessels.
c. Mollusks have a well-developed respiratory system, such as gills or lungs, but the respiratory systems of annelids vary, and some have specialized structures for gas exchange.
d. While some mollusks and annelids can reproduce asexually, it is not a characteristic shared by all species within these groups.
Therefore, the correct answer is option (a), as both mollusks and annelids have true coeloms.