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3 years ago

What are the mechanisms of natural selection, and how do they lead to changes in

1 answer:

5 0

Darwin's proposed mechanism for evolution is natural selection. Natural selection allows species to respond to their surroundings through time, or to become progressively excellently-suited. Natural selection is environmentally based and involves established heritable variation within a population.

They lead to changes in species over time:

Darwin suggested species will evolve over time, new species originate from pre-existing species, and all species share a common ancestor with each other.
In this framework each organism has its own special set of heritable i.e genetic variations from the common ancestor that have slowly developed over very longer periods of time.
Parroted branching activities that isolate new species from a common ancestor create a multi-level tree that connects all living organisms.

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In some protists, genetic information is transferred from one cell to the next. This transfer is called _____. A. external fertilization.

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If a human has 23 pairs of chromosomes in every muscle cell of its body how many chromosomes will be in a human egg or sperm

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Each egg and sperm carry 23 chromosomes.

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3 years ago

Tay-Sachs, which is a recessive lethal disease, results only when individuals possess two copies of the disease-causing allele.

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Answer:

a. Heterozygous individuals may pass on their copy of the disease-causing allele to offspring.

Explanation:

Tay-Sachs, which is a recessive lethal disease ---- Let say the recessive lethal diseases is s

∴ it only results when an individual posses two copies of the diseases-causing allele i.e two copies of the disease will be ss.

Now, when two hetrozygous individuals crossed , it is obvious that each can pass on their copy of the disease-causing allele to the offspring.

Let show an illustration for the above statement.

Let the heterozygous individual be Ts, if Ts cross with another Ts;

we will have:

Ts × Ts

T s

T TT Ts

s Ts ss

the offspring are TT,Ts,Ts,ss

We can now see how the Heterozygous individuals pass on their copy of the disease-causing allele to the offspring (Ts).

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3 years ago

The organisms that harness non-biological energy and convert it to biologically relevant/useful energy are called __ 1 __ _. The

mamaluj [8]

Answer:

The organisms that harness non-biological energy and convert it to biologically relevant/useful energy are called __autotrophos or producers_. The organisms that consume these are called _herbivores_ (it should end in -ores) which occur at the __second_ trophic level. The number of trophic levels that any ecological system will primarily dependent on the _consumer_ organisms.

Explanation:

In the trophic web occurs energy transference through organisms occupying different levels in the chain. Each level feeds on the preceding one and becomes food for the next one. The first link is occupied by autotroph organisms, which are the producer. The following links are the consumers: herbivores are primary consumers and feed on producers. Carnivores are secondary consumers and feed on herbivores, and so on. The last links are the decomposers, microorganisms that act on dead animals degrading organic matter.

Every link has an effect on the superior links and the immediately anterior link, meaning that whenever one of the links changes, the other ones will be affected.

Autotrophs or producers synthesize inorganic substances, such as light, and turn them into organic matter according to their own needs. These organisms are photoautotrophs, such as plants, or chemoautotrophs. They occur at the first trophic level.

Heterotrophs are those incapable of producing their own organic matter, so they feed on producers, depending on them to get proteins and energy. In the trophic chain, heterotrophic organisms occupy the first, second, or third consumer level, after producers. These animals can be herbivorous, carnivorous, omnivorous, hematophagous, ichthyophagous, and etcetera. All of them depend on autotrophic organisms.

In the particular case of herbivores, they occur at the second throphic level feeding on producers and being eaten by carnivores.

In general, most trophic chains are composed of 4 or 5 levels, depending on the number of consumers present, and the energy transference between levels.

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3 years ago