D. Organisms specialized for living in a particular niche.
Answer:
Jaws and a swimming bladder
Explanation:
A defining characteristic between sharks and rays that distinguish them from ray-finned fish is the *possession of jaws in sharks* and rays;and the *possession of swimming bladder in ray-finned fishes*.
Characteristics of sharks and rays are as follows :
They are cartiiliginous fishes; they possess *strong jaws* lined with teeth; body dorsoventrally flattened, fusiform (spindle shaped) with heterocercal tail(diphycercal in Chimaeras); paired fins; *no swimming bladder or lungs*; pelvic fins in males often modified to form clappers; Gill arches internal to gills; reduced notchord; lateral-line system; paired nostrils; internal nares absent; separate sexes; internal fertilization and direct development; oviparous, oviparous, or ovoviviparous. Examples include, Spiny dog fish or dog shark, Ray Raja, Chimaera.
Characteristics of ray-finned fishses:
They generally lack paired fins; no internal nares; *air sacks usually function as swimming bladder*; skeleton usually well ossified. Blind olfactory sacs (do not open into the mouth); Tail homocercal. Examples include Tilapia, Claris,and Polypterus.
The correct answer is B.
On this graph we can observe the workings of the stabilizing selection. Stabilizing selection tends to favor the average phenotype and eliminate the extremes. Essentially, this means that the natural selection is selecting the mean value of a trait as optimal. In our case, the mean weight of newborns is selected as optimal, because newborns born with less weight can be too weak to survive and the ones that have too much weight (are too big) can hurt the mother during birth.
The labeled anatomical features of the muscle filament are attached as an image.
Muscle filament or Myofilaments are the two protein filaments of myofibrils in muscle cells. The two proteins are myosin and actin and are the contractile proteins involved in muscle contraction.
- It has two filaments, a thick one made up mostly of myosin, and a thin one composed mostly of actin
- Actin is a filament made up of protein that contributes to the contractile property of muscle. It is found in two forms, G-actin (monomeric globular actin) and F-actin (polymeric fibrous actin)
- Tropomyosins are contractile proteins that regulate contraction in both muscle and non-muscle cells with help of myosin and actin filaments. It is present in animal cells.
- A troponin complex is a group of three proteins, troponin T, troponin I, and troponin C, subunits located on the thin filament of the contractile apparatus.
Thus, the correct labeled anatomical features of the muscle filament is attached as an image.
Learn more about Actin and myosin:
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