Answer:
Option 2: Spiracles.
Explanation:
Cartilaginous fish (also called Chrondricytes) have a skeleton of cartilage, instead of bone. There are two subclasses - Elasmobranchii and Holocephali. Sharks, rays, skates and sawfish are elasmobranchs while chimeras are holocephali.
Here’s a list of features of cartilaginous fish in comparison to bony fish:
1. Cartilage skeleton: unlike bony fish that have a skeleton made of bones (just like other terrestrial vertebrates), the skeleton of cartilaginous fish is made of cartilage.
2. Spiracles: this is a modified gill of sorts, it aids with respiration and is found slightly behind each eye. It leads directly to the mouth. Most cartilaginous fish possess this organ (exceptions are present, such as hammerhead sharks). Bony fish do not possess spiracles.
3. Ampullae of Lorenzini: absent in bony fish, these organs are electroreceptors that form a network of pores filled with a form of jelly that can transmit electrical signals. It allows the cartilaginous fish to sense electric fields in the water (such as the movements of a fish struggling), magnetic fields and temperature. Some bony fish such as sturgeon and lungfish may possess these organs, however research is still ongoing.
4. Claspers: male cartilaginous fish possess an organ known as claspers at their pelvic fin. This is used during reproduction to transfer the sperm into the female for fertilisation. As such, internal fertilisation occurs in cartilagonous fish. Bony fish do not possess this organ, and external fertilisation occurs.
There are many other characteristics that differentiate cartilaginous fish from bony fish. They're an extremely fascinating group of animals that unfortunately, is decreasing in numbers. Very little is known about many of these animals, so it is important that we do our best to conserve the sharks, rays, sawfish and chimeras before we lose them forever.
Answer is (E) : Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
Let me explain you why. Hershey and Chase conducted their experiment to show what is the genetic material that passes from one generation to another generation. Is it protein or DNA? For explaining this, they allowed the virus to grow in the presence of two different radio active elements.
In one set they grew viruses in the presence of P-32 radio-active element
In another set they grew viruses in the presence of S-35 radio active element.
The reason why they choose these two radio-active element was, phosphorus is present in DNA but not in proteins and similarly sulphur is found in proteins but not DNA.
These viruses were allowed to infect bacteria and the later was observed to be radio-actively labelled with P-32 but not S-35. This clearly showed that DNA is the genetic material which was passed from virus to bacteria.
Now if you choose Nitrogen for labeling, it won't help you in getting any conclusion since nitrogen is present in both proteins and DNA.
Answer:
Explanation:
Humidity is the measure of the amount of water vapor in the air.
Areas with a large amount of surface water have high humidity levels.
.Warm tropical areas have very humid air.
Answer:
lagoon
Explanation:
As the estuary gets more and more sediments, the deposition of them is constantly on the rise, affecting the landscape and forming new geographical features. With the sediments constantly building up, they eventually cut off part of the water from the sea. They will form a closed pool-like feature, filled with water, and surrounded by sediments, cut off from the sea. It will have shallow water, and because the water is stagnant and shallow it will have higher temperature than the other water. This geographical feature is known as lagoon.
If a person falls asleep while talking, riding a bike, standing or while doing physical activities, it should not be taken casually. It is a sign of a severe sleep disorder.
Narcolepsy is a neurological condition where the brain's ability to control the sleep-wake cycle is disrupted. In such case the patient can fall into Rem sleep after falling asleep for 90 minutes.
Nolan's behavior indicates that he is suffering from Narcolepsy and must consult a sleep clinic.
