Need help with these---
14. Which of the following is present in an insect but not in arachnids?
a. mandibles
b. compound eyes
c. jointed appendages
d. segmentation
16. The exoskeleton of an insect
a. does not have any muscles attached to it
b. is moved by muscles that are attached to the inside of the exoskeleton
c. is thickest where the joints of the appendages are located
d. is moved only by muscles attached to the wings
-MC
To answer question 14, we need to compare the characteristics of insects and arachnids. Here's how you can approach it:
1. Understand the characteristics of insects: Insects are a class of invertebrates that typically have a body divided into three segments (head, thorax, and abdomen), three pairs of jointed legs, compound eyes, and one or two pairs of wings.
2. Understand the characteristics of arachnids: Arachnids are another class of invertebrates that include spiders, scorpions, ticks, and mites. They have a body divided into two main parts (cephalothorax and abdomen), four pairs of jointed legs, and simple eyes (not compound eyes).
Now, let's analyze each choice for question 14:
a. Mandibles: Mandibles are a pair of jaw-like appendages used by insects for biting and chewing. Arachnids, on the other hand, typically have chelicerae instead of mandibles.
b. Compound eyes: Compound eyes consist of many individual lenses, which provide a wide field of view. Insects have compound eyes, while arachnids have simple eyes.
c. Jointed appendages: Both insects and arachnids have jointed appendages. This characteristic is not exclusive to insects.
d. Segmentation: Insects have segmented bodies divided into head, thorax, and abdomen. Arachnids, however, have only two main body parts and lack the same level of segmentation as insects.
Based on the above analysis, the correct answer for question 14 is b. Compound eyes.
Moving on to question 16:
The question asks about the exoskeleton of an insect. To determine the correct answer, let's evaluate each option:
a. The exoskeleton does not have any muscles attached to it: This is not true. Muscles are attached to the inner surface of the exoskeleton, allowing the insect to move.
b. The exoskeleton is moved by muscles attached to the inside of the exoskeleton: This is the correct answer. The muscles inside the exoskeleton contract and relax, causing the movement of the exoskeleton and the attached appendages.
c. The exoskeleton is thickest where the joints of the appendages are located: This is not necessarily true. The exoskeleton may be thicker in some areas, but it is not solely concentrated at the joints.
d. The exoskeleton is moved only by muscles attached to the wings: This is incorrect. While muscles attached to the wings enable flight, an insect's exoskeleton generally controls the movement of its entire body, not just the wings.
Therefore, the correct answer for question 16 is b. The exoskeleton is moved by muscles that are attached to the inside of the exoskeleton.