B. Composition mostly hydrogen and helium gas Mass 1.989 × 10³⁰ kg
Explanation:
The best data that describes the sun is that it's composition is made up of mostly hydrogen and helium gas with a mass of about 1.989 x 10³⁰kg.
- The sun is the largest body in our solar system and all planetary bodies revolves round it.
- At the core of the sun, nuclear fusion is occurring.
- Here, small atomic nuclei combines into larger ones with the release of a large amount of energy.
- The small nuclei are hydrogen and they produce helium.
- This process produce energy for the whole solar system.
- The sun is best defined as giant hot ball of gases.
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Pumping blood in and out of the heart.
54. Amphibians are cold-blooded animals, meaning they do not have a constant body temperature but instead take on the temperature of their environment. They have moist, scaleless skin that absorbs water and oxygen, but that also makes them vulnerable to dehydration (loss of bodily fluids).
55. The first and foremost characteristic of the reptiles is that are cold blooded. They are able to regulate their inner body temperature to the temperature of the environment. They have scaly skins but absence of hair or fur. The scales of the reptiles develop as a surface cells filled with Keratin.
56. Characteristics of Birds. Birds are endothermic and, because they fly, they require large amounts of energy, necessitating a high metabolic rate. As with mammals, which are also endothermic, birds have an insulating covering that keeps heat in the body: feathers.
57. Mammary Glands.
Undercoat and Guard Hair.
Jaw and Ear Bones.
Four-Chambered Heart and Diaphragm.
Complex Brain Functions.
Answer:
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The reason why eukaryotic cells are in need of turning on
and off their genes when necessary because of the reason that they may feel
stress because they are under stress as they have the responsibility of acting
immediately when they needed and by that, they need to be turned on or off in means
of adapting to the stress that they experience.
