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Explanation:

The exoskeleton and molting

The success of arthropods derives in large part from the evolution of their unique, nonliving, organic, jointed exoskeleton (see figure), which not only functions in support but also provides protection and, with the muscle system, contributes to efficient locomotion. The exoskeleton is composed of a thin, outer protein layer, the epicuticle, and a thick, inner, chitin–protein layer, the procuticle. In most terrestrial arthropods, such as insects and spiders, the epicuticle contains waxes that aid in reducing evaporative water loss. The procuticle consists of an outer exocuticle and an inner endocuticle. In the exocuticle there is cross-bonding of the chitin–protein chains (tanning), which provides additional strength to the skeletal material. The hardness of various parts of the exoskeleton in different arthropods is related to the thickness and degree of tanning of the exocuticle. In crustaceans, additional rigidity is achieved by having the exoskeleton impregnated with varying amounts of calcium carbonate.

arthropod integument

arthropod integument

Diagrammatic section through the arthropod integument.

Encyclopædia Britannica, Inc.

The formation of an exoskeleton required the simultaneous solution of two functional problems in the evolution of arthropods: If the animal is encased in a rigid covering, how can it grow and how can it move? The problem of growth is solved in arthropods by molting, or ecdysis, the periodic shedding of the old exoskeleton. The underlying cells release enzymes that digest the base of the old exoskeleton (much of the endocuticle) and then secrete a new exoskeleton beneath the old one. At the time of actual shedding, the old skeleton splits along specific lines characteristic of the group, and the animal pulls out of the old skeleton as from a suit of clothes. The old skeleton is usually abandoned but in some species is eaten. The new exoskeleton, which is soft and flexible, is then stretched by localized, elevated blood pressure augmented by the intake of water or air. Hardening occurs by stretching and especially by tanning within a number of hours of molting. In crustaceans, calcium carbonate is deposited into the new procuticle. (Soft-shell crabs are simply newly molted crabs.) Additional endocuticle may be added to the exoskeleton for some days or weeks following molting.

molting

molting

Grasshopper shedding its exoskeleton.

© Cathy Keifer/Dreamstime.com

Molting is under hormonal control, and there is a long preparatory phase that precedes the process. The steroid hormone ecdysone, secreted by specific endocrine centres and circulated in the blood, is the direct initiator of molting. The actual timing of a molt, however, is regulated by other hormones and commonly by environmental factors. The interval between molts is called an instar. Because of the frequency of molts, instars are short early in life but grow longer with increasing age. Some arthropods, such as most spiders and insects, stop molting when they reach sexual maturity; others, like lobsters and crabs, molt throughout their lives. Most of the larger spiders of temperate regions, for example, molt about 10 times before reaching sexual maturity. As a result of molting, the length and volume of an arthropod display steplike increases over the life span, but internal tissue growth is continual as in other animals.

Loss of a limb is a common hazard in the life of many arthropods. Indeed, some arthropods, such as crabs, are capable of amputating an appendage if it is seized by a predator. The limb is then regenerated from a small, nipplelike rudiment formed at the site of the lost limb. The new limb develops beneath the old exoskeleton during the premolt period and then appears when the animal molts.

Answer:

Three layers

Explanation:

Outer= Composed of proteins and lipids. Repels water and prevents desiccation in terrestrial places.

Middler=Provides primary protection

Inner=Flexibke at joints, muscles attach here.

Answer:

probability of a prime no. coming up is 3 : 1

probability of a head coming up. is 2 : 1

this isn't biology btw..

it says it all sorry

Answer:

Commensalism is a symbiotic relationship in which one species benefits while the other is not affected.

Explanation:

The organism of the ecosystem like the plants and the animals along with the microorganisms are connected and interlinked with one another through the ecological relationship.  The relation could be positive, negative or neutral.

Thus, symbiosis is important for the ecosystem.

Learn more about symbiosis here:

https://brainly.com/question/13889524

Answer:

Arctic sea

Hope it helps

um what are the anwsers for the question

Answer:

The correct answer is  All of the above. In nature there are four forces, (also called interactions or fields in Physics) that are responsible for all phenomena in the universe: the gravitational force or interaction, the strong interaction, the electromagnetic and the weak nuclear.

Explanation:

The fundamental interactions or forces that describe all the interactions between the constituents of matter are each of the interactions that matter can undergo and that cannot be decomposed into more basic interactions. There are four basic forces that describe all interactions: Gravitational, that is responsible for the interaction between particles with mass and, by extension, for the configuration on a macroscopic scale of the Universe and its stability. Electromagnetic, is responsible for the interaction between electrically charged particles and, by extension, for all Chemical reactions, Weak is responsible for the disintegration of certain unstable particles; that is, of those processes in which some particles decompose (decay) into lighter ones and Strong interaction is the most complicated interaction to describe due to its different behaviors at different action distances; by means of which a global vision of the to physics without breaking it down.

Wear protective gear (goggles, long-sleeved clothes, and gloves) when using acids and bases. Do not allow acids or bases to come in contact with skin or eyes. Limit the amount of acids and bases transported for usage around the house. Cap the bottles of acid and base cleaners tightly.

Answer:

Option A) is correct.

Explanation:

Electromagnetic waves refer to waves that are created due to vibrations between a magnetic field and an electric field.

Electromagnetic waves do not require a medium to travel through space without a medium. Electromagnetic waves can travel through air,  vacuum of space and solid materials.

So,

Option A) is correct.

Answer:  Photosynthesis has a role in the cycling of matter and flow of energy into and out of organisms.

Explanation:

The flow of energy and cycling of matter can be traced. The chemical reaction by which plants produce complex food molecules to occur requires an energy input

Answer:

They work together to keep things in orbit.

Explanation:

Gravity pulls things in, while inertia says that all celestial objects will try their best to continue forward. The results in the orbiting of celestial objects, like the Earth, around other celestial objects, like the Sun.

Answer:

(Source: sciencing.com)

Answer: I think it is B

Explanation:

Answer:

A. exhibit

Explanation:

The only logical response!

Answer:

A

Explanation:

exhibit

Answer:

Run-off

Explanation:

Water from land slides into streams and ponds are called run-off.

Answer:

A

Explanation:

I think an untreated water can carry disease causing organisms and make people sick

Answer:

option (C) is your answer

I hope it's helps you

Answer:

C.

Explanation:

I am so sorry if I'm the wrong answer.

Answer: The answer is D: Platyhelminthes

Explanation: took the test and it came back

Answer: the answer is b, abiotic

Explanation: Abiotic factors are the non-living parts of the environment that can often have a major influence on living organisms and Abiotic factors include water, sunlight, oxygen, soil and temperature.

Answer: D

Explanation:

Answer:

It will still attract.

Explanation:

When you think of it, when some of us were little we used magnets and played with them and would do a "magic" trick. We would put a magnet underneath the table and one on top and move the one underneath which would move the one on top without us touching it.

Hope this helps!!

Answer:

Muscle contraction function.

Explanation:

The nerve endings possess synaptic acetylcholine vesicles ready to be released. The action potential depolarizes the presynaptic terminal and increases the concentration of axoplasmic calcium; Acetylcholine molecules are thus released, so that the concentration of the neurotransmitter at postsynaptic (nicotinic) receptors is temporarily increased. This is followed by post-synaptic membrane depolarization, muscle membrane action potential with increased rnioplasmic calcium concentration, and finally muscle contraction. Acetylcholine is hydrolyzed by acetylcholinesterase and resynaptic at the presynaptic level by cholinecetyltransferase. The etiopathogenesis of myasthenia gravis is autoimmune and there are antibodies against acetylcholine receptors that circulate in the blood, as well as a decrease in the number of receptors on the motor plates, that is, it is produced by the postsynaptic blockage of the myoneural plaque, that generates fatigue and localized or generalized muscle weakness that is characterized by the worsening of the contractile force of the muscle.

Answer: cell wall

Explanation:

Answer:

In anatomy, the notochord is a flexible rod formed of a material similar to cartilage. If a species has a notochord at any stage of its life cycle, it is, by definition, a chordate. The notochord lies along the anteroposterior ("front to back") axis, is usually closer to the dorsal than the ventral surface of the animal, and is composed of cells derived from the mesoderm.

Answer:

Excitation is the process in which action potentials in the nerve fiber lead to action potentials in the muscle fiber. There is then a rapid fluctuation in membrane voltage at the motor end plate, called the end-plate potential. Areas of the sarcolemma near the motor plate have gates that open, moving ions, which causes the action potential that excites the muscle fiber. The process begins with a nerve signal stimulating a voltage-gated calcium ion channel to open, allowing the ions to enter the axon terminal. The ions stimulate the release of acetylcholine into the synaptic cleft.

Answer:

At D

it spreads at the mid ocean ridge ig

Answer:

Without decomposers, dead leaves, dead insects, and dead animals would pile up everywhere. And most importantly decomposes make vital nutrients available to an ecosystem primary producers- usually plants and algae.

Answer:

B

Explanation:

abcdefghijklmnopqrstuvwxyz

Answer:

C. A hillside that has been cleared by a volcanic eruption.

Explanation:

Pioneer species are hardy species which are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by fire or other natural disasters. Some lichens grow on rocks without soil, so may be among the first of life forms, and break down the rocks into soil for plants.

Hope this helps!

Answer:

9:7

Explanation:

We get the dominant phenotype in plants that have at least one dominant allele of EACH of the two genes; otherwise, we get the recessive phenotype. So, the observed ratio in the F2 generation is 9:7.

Answer:

True.

Explanation:

Yes, the number of heavy storms has increased due to global warming because of the holding power of moisture by the atmosphere due to higher temperature. When the air is warmed, the air can hold more water at that temperature so due to more holding power of moisture by the air the number of storms increases. One NASA study supports that global warming is causing the increase in number of extreme storms especially in the tropical ocean.