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2 years ago

9

For what part of the day did only unicellular life-forms exist?

1 answer:

Ronch [10]2 years ago

6 0

Question:

For what part of the day did only unicellular life-forms exist?

Answer:

The first known single-celled organisms appeared on Earth about 3.5 billion years ago, roughly a billion years after Earth formed. More complex forms of life took longer to evolve, with the first multicellular animals not appearing until about 600 million years ago.

Question:

At what time of day did the first plants appear on earth?

Answer:

The first land plants appeared around 470 million years ago, during the Ordovician period, when life was diversifying rapidly. They were non-vascular plants, like mosses and liverworts, that didn’t have deep roots.

Question:

At what time of day did mammals appear on earth?

Answer:

The period between the extinction of the dinosaurs and the present day is called the Age of Mammals or Cenozoic. Mammals appeared on the earth long before the extinction of the dinosaurs; in fact, dinosaurs and mammals originated within 10 million years of each other, in the late Triassic about 200 million years ago.

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How does newtons law of universal gravitation apply to earth and the moon

Nataly [62]

Newton proved that the force that causes, for example, an apple to fall toward the ground is the same force that causes the moon to fall around, or orbit, the Earth. This universal force also acts between the Earth and the Sun, or any other star and its satellites. Each attracts the other.

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3 years ago

In pea plants, tall plants (T) are dominant to short plants (t). If two heterozygous (Tt) individuals are crossed, what percent

nydimaria [60]

Answer:

1

Explanation:

T t

T TT Tt

t Tt tt

8 0

3 years ago

In response to seasonal changes in temperature, many organisms must alter the composition of their plasma membranes to maintain

katrin [286]

Answer:

The correct answer is D

Explanation:

The cell membrane is essentially composed of the following:

phospholipids
cholesterol
proteins

The phospholipid consists of a <em>hydrophilic </em>phosphate 'head' and the tail is the <em>hydrophobic</em> fatty acid chain.When cellular membranes form,phospholipids collect into two layers in light of these hydrophilic and hydrophobic properties. The phosphate heads in each layer face the fluid or watery condition on either side, and the tails conceal away from the water between the layers of heads, since they are hydrophobic.

There are 3 main factors that greatly influence the fluidity of the plasma membrane:

temperature
cholesterol
saturated and unsaturated fatty acids

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2 years ago

All of the following are regulatory functions of the endocrine system except Select one: a. labor contractions. b. development o

aleksley [76]

Answer:

c. immune functions.

Explanation:

The endocrine system is involved in the regulation of metabolic rate, body temperature (thermoregulation), tissue development and labor contractions except immune functions.

Studies have shown that no hormone has been identified as being important in the regulation of the immune system. Therefore immune functions is not a regulatory function of the endocrine system.

Although, there have been articles on the endocrine and immune system crosstalk, only a hypothesis of various proteohormones not single hormones have been discovered to act on immunocompetent cells.

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3 years ago

Explain why is important for hydrogen bonds to be weak bonds instead of very strong bonds.

lesantik [10]

Hydrogen bonds are classified as weak because they are formed fast, but they also break easily under normal biological conditions.

Weak bonds can be easily broken, but this is extremely important because they are in bold in biological systems. For example, they help to decide and stabilize the shapes of water molecules.

4 0

3 years ago