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dem82 [27]
3 years ago
15

The theory of evolution by natural selection was proposed in the origin of species by means of natural selection (1859) written

by
Biology
1 answer:
sp2606 [1]3 years ago
5 0
It was proposed by a scientist named Charles Darwin.
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Realiza la configuracion electronica,la CEE,grupo y periodo,de cada elemento,la estructura de lewis y la formula de sarrollada d
lesya692 [45]

Answer:

1s2 2s2 2p4

Explicación:

1s2 2s2 2p4 es la configuración electrónica de la molécula de agua. En el agua, hay 10 electrones, dos de hidrógeno y ocho de oxígeno. La subcapa 2s contiene un máximo de 2 electrones, mientras que la capa 2p puede acomodar seis electrones. El átomo de hidrógeno pertenece al primer grupo y el átomo de oxígeno pertenece al sexto grupo de la tabla periódica. En la estructura de Lewis, un átomo de oxígeno está unido a dos átomos de hidrógeno en un ángulo de 104,45 grados. Existe un enlace covalente presente entre el hidrógeno y el átomo de oxígeno en el que ambos se vuelven estables. El oxígeno necesita dos electrones, por lo que forma enlaces con dos átomos de hidrógeno que tienen un electrón cada uno.

3 0
3 years ago
Bio 254 - Pre-Class Assignment 1
Trava [24]

Question 1:

<u>Answer</u>:

The "first line of defence" in innate immunity is "Physical and chemical barriers".

<u>Explanation</u>

"Physical and chemical barriers" is first line of defence includes  that are  ready to defend the living organism's body from infection at any time . These barriers include your skin, cilia, tears, urine flow, mucus, stomach acid, friendly bacteria and white blood cells . Skin acts as a mechanical barrier as it does not allows all the organism to pass through it unless the skin is cut or open. Similarly mouth eyes, and nose are also the ways through with the disease causing organism can enter the body. The micro-organisms that entered through these pathways are trapped either in saliva or mucus and swallowed and later either killed in the stomach or flushed out via the urine. If this first line of defence is broken or damaged, the second line of defence inside our body will be activated.

Question 2:

<u>Answer:</u>

Histamine kinins, and interleukins are examples of inflammatory mediators.

<u>Explanation</u>:

Inflammatory mediators are identified in inflammatory bowel disease IBD.These mediators play an vital role in the clinical and pathologic characteristics of the disorders. Cytokines, that are released by macrophages in due to antigenic stimuli, are binded different receptors and produce endocrine, autocrine and paracrine effects.  Interleukins are a subset of a large group of 'cellular messenger molecules' called cytokines that modulates the cellular behaviour. Interleukins are not stored within cells like cytokines but they are released immediately, in response to a stimulus. Once an interleukin has been secreted, it moves to the target cell and binds to it through a receptor molecule on the surface of the cell . This interaction triggers a sequence of  signals in the target cell that ultimately leads to the alteration in the behaviour of the cell.

5 0
3 years ago
River deltas are _____. formed by erosion created by seafloor spreading caused by the movement of tectonic plates areas of infer
Basile [38]
Formed by erosion created by seafloor spreading

RIVER DELTAS ARE formed by erosion created by seafloor spreading

NOT:
caused by the movement of tectonic plates areas of infertile, rocky soil
3 0
3 years ago
Read 2 more answers
Does sound travel/propagate through a medium?​
NeTakaya

Answer:

Sound is a sequence of waves of pressure which propagates through compressible media such as air or water. (Sound can propagate through solids as well, but there are additional modes of propagation). ... Independent of the motion of sound through the medium, if the medium is moving, the sound is further transported.

please mark as branliest

4 0
3 years ago
In sedimentary rock the oldest fossils would be expected to be found In the top layer of rock In the middle layers of rock In th
a_sh-v [17]
<span>When sediments move and settle somewhere, they are being deposited. When, over a long time, layers and layers of sediments get deposited on top of each other, the weight of the top layers presses down on the bottom layers, forming them into rock called sedimentary rock. The oldest layers are on the bottom, and the youngest layers are on the top. Because sediments sometimes include once-living organisms, sedimentary rock often contains a lot of fossils. </span>
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3 years ago
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