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Dafna11 [192]
3 years ago
6

Although earth is estimated to be 4.5 billion years old, and although life first appeared about 4 billion years ago, plants did

not appear until about _______ years ago.
Biology
1 answer:
timurjin [86]3 years ago
3 0
470 million years ago
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The transport tubes from food came down the plant are called?
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Tubes for Transporting Food-carrying tubes Phloem Water-carrying tubes Xylem Sugar is produced In the leaves. The food-carrying tubes transport this sugar from the leaves to the other parts of the plant. The root hairs found on the roots Take in water and mineral salts from the soil.


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A population is _____.
goldenfox [79]
The answer to this is a group of individuals many species living in an area.
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which information must be known about a compound to find the molecular formula from the empirical formula​
LenKa [72]

Answer:

Molecular mass or vapor density

Explanation:

The empirical formula is the simplest formula of a compound. The molecular formula expresses the exact formula of the compound. To derive the molecular formula, we need information about its molecular mass or if given the vapor density.

                (Empirical Formula)n = Molecular formula ------(i)

         n = number of repeating units of the empirical formula present in one                        mole of the molecule

          also, (molar mass of empirical formula)n = molar mass of compound

      From here, we can find n and insert in (i) above.

4 0
3 years ago
Cell division is preceded by two growth phases. Besides growth, both G1 and G2
Leviafan [203]

Answer:

A

Explanation:

a. contain checkpoints that determine if the cycle will continue.

b. help move chromosomes to the new daughter cells.

c. produce more chromosomes before the cell divides.

d. grow and produce enough cytoplasm to fill two cells.

<em />

<em>The correct answer would be that G1 and G2 contain checkpoints that determine if the cycle will continue or otherwise.</em>

The cell cycle generally has three checkpoints that happen at G1, G2, and M phase of the cycle.

At G1 checkpoint, the integrity of the DNA of the cell is assessed to ensure that there are no damages and other conditions such as size and energy reserve are checked.

At G2 checkpoint, the cell is assessed for proper chromosome duplication to ensure that there are no mistakes or damages. The size of the cell and the amount of protein are also checked to ensure that the cell is ready for the active division phase.

At M checkpoint, correct attachment of the spindle fiber to the kinetochore of the chromosomes is checked. This checkpoint is also known as the spindle checkpoint and it happens towards the concluding phase of the metaphase stage.

<u>The correct option is therefore, A.</u>

6 0
3 years ago
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