Question

The diagram below shows a portion of the geologic time scale.



Based on the time scale, which of these inferences is most likely correct?

land animals created the first oxygen molecules

flowering plants created the first oxygen molecules

rock formation started after microscopic life appeared on Earth

the atmosphere was formed after microscopic life appeared on Earth

Answer 1

@whpalmer4 can you help?

Answer 2

@abb0t do you know this?

Answer 3

I'm not sure, but I would say it's between choice 2 or 4? But i'm leaning towards 2 just because flowers make oxygen.
It can't be A because oxygens don't make oxygen, we breathe oxygen. And I don't think it's the (C) because rock formation is I think, made of different elements? So I don't think microscopic life had anything to do with it.

Answer 4

okay thanks can you help with a few more?
@abb0t

Answer 5

I can try.

Answer 6

Which of these best matches a source of information with its most reliable use?

root structures → comparison of the evolution of land animals

root structures → comparison of the evolution of plant eating organisms

fossil records → comparison of the evolution of frogs and birds

fossil records → comparison of the evolution of completely soft-bodied organisms
@abb0t

Answer 7

Hmm...what's a root structure?

Answer 8

roots as in plant roots or roots as in ancestry?

Answer 9

im honestly not sure!, which one would make more sense?
@abb0t

Answer 10

Did you look up "root structures" in your textbook or online on Wikipedia?

Answer 11

its an online class and it shows up no where so idk ill just skip it and move on, thenext one is:

The table below shows the initial and final masses of a radioactive material in a container.

Initial mass (in kilograms) 0.8
Final mass (in kilograms) 0.05

Based on the table, which of these conclusions is correct?

The half life of the material is three years.

The half life of the material is four years.

The mass of the material was 0.1 kilograms after four half lives.

The mass of the material was 0.1 kilograms after three half lives.

Answer 12

@abb0t

Answer 13

@rajathsbhat can you help with these?

Answer 14

Half life is defined as the time it takes for a radioactive material to reduce to half it's original mass (it's like radioactive materials poop out radiation. So they lose mass)
So, if the original mass was 0.8g, 1 half life is the time it takes for this chunk of material to reduce to 0.4g. Do you get it up to here?

Answer 15

no not really idk what the answer would be from tehre because thats not really a choice? :/ @rajathsbhat

Answer 16

forget about the answer. We're getting there. The important thing is that you understand what you're doing so that you can ace this question like a boss. I want you to first understand what a 'half life' means.

Answer 17

i do i think, its basically you divide the substance or number in half so its seeing how many 'half-lives' a substance takes to completely dissapear and reach 0 right?

Answer 18

yes, you're right. but notice that no matter how many times you divide in half, you'll never get to 0.

Answer 19

i need this help asap because im in the process of being timed for this hard test!! please help quick i have like 7 more i need help with im begging or i will fail this course

Answer 20

yea i realized it wasnt 0 when i kept dividing so i don t understand the answer

Answer 21

its D right?

Answer 22

all you have to do is count the number of times you divide by half to get 0.05g from 0.8g. Makes sense?

Answer 23

how many times do you have to divide 0.8g by 2 to get 0.05g?

Answer 24

3 right?

Answer 25

do you get this one:

Which of these statements is correct about how the first forms of life appeared on Earth?

Non-living molecules evolved into living molecules by chemical changes.

Reproducing molecules evolved into living organisms by biological processes.

Rocks and fossils were transformed into living molecules by biological processes.

Atmospheric gases were transformed into living organisms by chemical changes.

Answer 26

0.8--->0.4--->0.2--->0.1--->0.05
how many arrows is that?

Answer 27

but D says The mass of the material was 0.1 kilograms after three half lives.
and thats true

Answer 28

whoops sorry. Didn't notice that. In that case, it's D, yes.

Answer 29

okay thnk you(: now what about that next question i just posted???? please help

Answer 30

uhh i haven't really studied biology so i don't know :\

Answer 31

do you know anyone else who would be able to help?

Answer 32

what about this one:

One scientist kept 64 grams of a radioactive material in a container. After how many half lives will 1 gram of radioactive material be left in the container?

Answer 33

the choices are 2, 4, 6, or 8? i chose 6 but wasnt sure?
@rajathsbhat

Answer 34

@some_someone do you know? :)

Answer 35

@some_someone PLEAASE HELP

Answer 36

ok so for: Which of these statements is correct about how the first forms of life appeared on Earth?
i would say it is: Non-living molecules evolved into living molecules by chemical changes.

Answer 37

thank you, what about this one:

Which of these best matches a source of information with its most reliable use?

root structures → comparison of the evolution of land animals

root structures → comparison of the evolution of plant eating organisms

fossil records → comparison of the evolution of frogs and birds

fossil records → comparison of the evolution of completely soft-bodied organisms