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vaieri [72.5K]
3 years ago
11

Please send help also 20points

Biology
2 answers:
Makovka662 [10]3 years ago
6 0

Answer:

An echo occurs when a sound wave reflects back towards its source after hitting a hard surface.

You are right!

frosja888 [35]3 years ago
6 0

Answer:sound wave

Explanation: Echo is a sound heard after a sound wave hit a hard surface. The sound is what is heard back as echo. An echo doesn't occur when the sound wave have been absorbed before hitting an hard surface so in a large crowd you might not hear an echo because the sound wave have been absorbed. The echo is heard faster when you are standing close to a hard surface than when you are far away a hard surface.

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Enzymes are a type of catalysts.

3 0
3 years ago
Hormones are chemical molecules produced by endocrine glands. One such endocrine gland is the thyroid gland, which synthesizes t
mixas84 [53]

Answer:

The right answer is 1 and 4

Explanation:

A hormone is a biologically active chemical substance, synthesized by a glandular cell secreted into the internal environment where it circulates, acting remotely and by blood on receptors specific to a target cell. It transmits a message in chemical form and therefore plays a role of messenger in the body.

The emitting organ thus acts at a distance on all of the target organs of the organism or of neighboring organisms of the same species, or even of symbiotic organisms whose receptors are activated in contact with specific hormones (lasting interactions).

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2 years ago
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Semenov [28]

Answer:

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5 0
3 years ago
In which of the following ways can scientific knowledge change and grow?
allochka39001 [22]

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4 0
3 years ago
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Which body cells always or sometimes carry out the anaerobic energy extraction pathway? A. Red blood cells and muscle cells. B.
ExtremeBDS [4]

Answer:

A. Red blood cells and muscle cells.

Explanation:

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