Advanced science 7. grade 7.

can anyone me answer these science questions soon as possible?

1. a duplicated chromosome is two sister chromatids joined by a ?

2. during the mitotic phase, first the nucleus then the cytoplasm divide. true or false?

3.the three main types of plant tissue are dermal, vascular and epithelial tissue. true or false?

4. what does nervous tissue do?
causes movement
forms the protective outer layer of skin
carries messages to and from the brain
provides structure and support

5. which of the following organisms do not have genetic variation?
hydra
trees
dogs
humans

6. explain how organisms produced through sexual reproduction differ from those produced by asexual reproduction. discuss what the advantages or disadvantages might be for each.

7. america is made up of states. one state, ohio, is made of counties. each county is made of townships. what is the similar progression from organism to cell?

On a recent expedition to a remote region of northern canada, scientists uncovered skeletal remains from about 100,000 years ago. surprisingly, all the skeletal remains, which included many species from differing biological families and spanned about two thousand years, showed evidence of experiencing temperatures in excess of 1000 degrees fahrenheit (or 538 degrees celsius). which of the following, if true, best explains the apparent paradox between the cold environment and the evidence of the bones experiencing hot temperatures? (a) chemical changes that naturally occur during the process of decay in only one north canadian species produce the same evidence of the species' skeletons being exposed to hot temperatures as the expedition scientists found. (b) a little over 103,000 years ago, a large fire is known to have occurred in northern canada. (c) strong evidence exists that as early as 70,000 years ago, homo sapiens around the world relied heavily on fire to cook animals. (d) in the same expedition and in roughly the same layer of excavation, scientists found rudimentary wood cutting and hunting tools used by early humans.

How is ribosomal rna useful as a molecular clock? a. a large portion of the dna ring is not vital to structure or function, allowing it to accumulate neutral mutations. b. its rate of mutation increases over time as organisms continue to evolve and differentiate from each other. c. a slow mutation rate makes it useful for determining evolutionary relationships between ancient species. d. it is only found in select organisms, making it easier to compare relationships between species that have it.

Which coal field location is related to coal fields in the eastern united states and supports the theory of continental drift? eastern india southern africa western australia northern south america