Placoid
A)scales that resemble a tooth, having a broad base and a narrow pointed top
B)an organ for breathing underwater, consisting of membranes through which oxygen can pass
C)an organ along the side of a fish that can detect movement in the water
D)a deep sea fish with a skeleton of cartilage
E)a flap covering the gills of a bony fish
A) scales that resemble a tooth, having a broad base and a narrow pointed top.
3.
What statement accurately describes the relationship between variations and fitness?
The relationship between variations and fitness is that variations in a population can affect an individual's ability to survive and reproduce in a given environment, leading to differences in fitness among individuals and potentially resulting in natural selection and evolution of the population over time. Individuals with advantageous variations that increase their fitness have a better chance of surviving, reproducing, and passing their beneficial traits to their offspring, while individuals with less advantageous variations may struggle to survive or reproduce. Therefore, variations play a crucial role in determining an individual's fitness and the overall genetic makeup of a population.
The term "placoid" refers to a specific characteristic or feature found in certain organisms, particularly in fish. To determine the correct answer, we can break down each option and determine which one accurately describes the term.
A) Scales that resemble a tooth, having a broad base and a narrow pointed top: This option describes placoid scales, which are commonly found in cartilaginous fish like sharks. These scales are tough and tooth-like in appearance, tapering to a pointed tip.
B) An organ for breathing underwater, consisting of membranes through which oxygen can pass: This describes gills, which are not specifically related to placoid.
C) An organ along the side of a fish that can detect movement in the water: This describes the lateral line, which is not specifically related to placoid.
D) A deep-sea fish with a skeleton of cartilage: This describes cartilaginous fish, such as sharks or rays, which have a skeleton made of cartilage. While they may have placoid scales, the focus here is on the type of fish rather than the specific characteristic.
E) A flap covering the gills of a bony fish: This describes an operculum, which is not specifically related to placoid.
Therefore, the correct answer is A) scales that resemble a tooth, having a broad base and a narrow pointed top.