How do rates of mutation "power" molecular clocks?

1 answer:

6 0

Molecular clocks use rates of mutation to measure evolutionary time. Mutations add up at a fairly constant rate in the DNA of species that evolved from a common ancestor. The more mutations that happened in each lineage, the greater is the differences between these lineages.

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What of the following can stoichiometry be used for?

storchak [24]

Calculating limiting and excess reactants?

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3 years ago

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Neville has low blood pressure and his pituitary started producing a homorone to maintain water balance his blood pressure event

ivanzaharov [21]

Answer: The options are missing in the question,the options are;

A) Positive feedback will stop the release of this hormone.

B) Positive feedback will speed up the release of this hormone.

C) Negative feedback will speed up the release of this hormone.

D) Negative feedback will stop the release of this hormone.

The correct answer to the question is option D

NEGATIVE FEEDBACK WILL STOP THE RELEASE OF THIS HORMONE.

Explanation: The hormone the will be produced is known as Antidiuretic hormone (ADH).it is otherwise known as VASOPRESSIN.It is secreted by the posterior lobe of the pituitary gland.

The main effect of Antidiuretic hormone is to reduce urine output,(diuresis is the production of large amount of urine). Antidiuretic hormone acts in the distal convulated tubules and the collecting ducts of the nephrons of the kidneys,it increases their permeability to water and more of the glomerular filtrate is reabsorbed. Antidiuretic hormone secretion is determined by the osmotic pressure of the blood circulating to the osmoreceptors in the hypothalamus.

As osmotic pressure rises,for example as a result of dehydration, secretion of Antidiuretic hormone increases. With this,there is Increased reabsorption of water reducing the amount of urine produced.This implies that more water is retained in the body making the rise in the osmotic pressure of the blood to be low,for example,after a large fluid intake, secretion of Antidiuretic hormone is reduced,less water is reabsorbed and more urine is produced.

At high concentrations,for example after severe blood loss, antidiuretic hormone causes smooth muscle contraction, especially vasoconstriction in small arteries.this has a pressor effect,raising systemic blood pressure.

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4 years ago

Food chains always start with which kind of organism? Question 3 options: Decomposer Consumer Carnivore Producer

Valentin [98]

Answer:

Producers!

Explanation:

Autotrophs are the foundation of every ecosystem on the planet. That may sound dramatic, but it's no exaggeration! Autotrophs form the base of food chains and food webs, and the energy they capture from light or chemicals sustains all the other organisms in the community. When we're talking about their role in food chains, we can call autotrophs producers.

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3 years ago

How does surface-to-volume ratio relate to the size of a cell

Lelu [443]

The answer is A. The ratio goes down as the size of the cell gets larger.

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4 years ago

Which statement represents an abiotic environmental factor in an ecosystem?

sukhopar [10]

Answer:

An example of an abiotic factor within an ecosystem is the air temperatures in the mountains.

Explanation:

In an ecosystem, abiotic factors refer to all those non-living elements, which depend on chemical and physical elements. Water, soil, wind, temperature, climate, minerals and soil pH are abiotic elements.

In comparison to the other statements, the one that corresponds to an environmental abiotic factor is the air temperature in the mountains, describing even two factors, air and temperature.

The other alternatives, lion hunting the gazelle, flower growing on the vine or fish swimming in the lake represent biotic or living elements of an ecosystem.

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3 years ago