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3 years ago

What was the source of the microscopic "animalcules" described by Leeuwenhoek?

1 answer:

3 0

With his superior light adjusting techniques, Leeuwenhoek was able to construct microscopes which could magnify over 200 times, enabling him to perceive small "animalcules" or bacteria in water.

Furthermore, in a letter, he reports how he had discovered in the plaque of two old men who had never brushed their teeth in their lives “an unbelievably great company of living animalcules, a-swimming more nimbly than any I had ever seen up to this time. The biggest sort. . . bent their body into curves in going forwards. . . Moreover, the other animalcules were in such enormous numbers, that all the water. . . seemed to be alive.”

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What are the three characteristics of all vertebrates

Rudiy27

Notchochord, morphology, chordates

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2 years ago

A researcher performs an experiment to test a hypothesis that involves the nutrients niacin and retinol. She feeds one group of

julsineya [31]

Answer:

- 100 grams of food A (x)

- 60 grams of food B (y)

Explanation:

According to this question, the group of laboratory rats are being fed a daily diet of:

- 125.6 units of niacin and 5,400 units of retinol

Let x represent the number of grams needed for food A.

Let y represent the number of grams needed for food B.

This means that:

Food A: Niacin = 0.86x, Retinol = 30x

Food B: Niacin = 0.66y, Retinol = 40y

Since there are 125.6 units of niacin fed to the rats in total, then;

0.86x (A) + 0.66y (B) = 125.6

Since there are 5400 units of retinol fed to the rats in total, then;

30x (A) + 40y (B) = 5400

Solving these two equations simultaneously using elimination method:

0.86x (A) + 0.66y (B) = 125.6 ........(eqn 1)

30x (A) + 40y (B) = 5400 ............ (eqn 2)

Multiply eqn 1 by 30 and eqn 2 by 0.86

30 × 0.86x + 0.66y = 125.6

0.86 × 30x + 40y = 5400

25.8x + 19.8y = 3768 ............ (eqn 3)

25.8x + 34.4y = 4644 ........... (eqn 4)

Subtract eqn 3 from eqn 4

14.6y = 876

Divide both sides by 14.6

y = 876/14.6

y = 60

Substitute value for y (60) into eqn 2

30x + 40y = 5400

30x + 40(60) = 5400

30x + 2400 = 5400

30x = 5400 - 2400

30x = 3000

x = 3000/30

x = 100

Therefore, she feeds the group of rats 100grams of food A (x) and 60 grams of food B (y).

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2 years ago

How does this model show what keeps Earth in orbit around the Sun?

anyanavicka [17]

Answer:

Explanation:

"Gravity is the force that pulls Earth and stops it from going off in some other direction.” Without the sun's gravitational pull, Earth would move in a straight line away from the sun. Gravity is also the force that keeps the moon revolving around Earth.

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1 year ago

Q14.The sodium atom contains 11 electrons, 11 protons, and 12 neutrons. What is the atomic mass number of sodium?

love history [14]

Answer: C

Explanation: The atomic mass is 22.990 so it would be C

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1 year ago

Diatoms are mostly asexual members of the phytoplankton. Diatoms lack any organelles that might have the 9 + 2 pattern. They obt

Brrunno [24]

Answer:

Diatoms are mostly asexual members of the phytoplankton. Diatoms lack any organelles that might have the 9 + 2 pattern. They obtain their nutrition from functional chloroplasts, and each diatom is encased within two porous, glasslike valves. Which question would be most important for one interested in the day-to-day survival of individual diatoms?

C) How do diatoms with their glasslike valves keep from sinking into poorly lit waters?

Explanation:

Diatoms are some of the most important organisms living on earth because of its role on the oxygen production in the planet earth. The question "how do diatoms with their glasslike valves keep from sinking into poorly lit waters?" Because of the way their nutrition is obtained from functional chloroplasts and the way them encased within two porous, glasslike valves.

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2 years ago