Answer:
B
Explanation:
because their structures become more complex. Such as the human brain, over time we get more knowledge.
There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms.
There are problems with each of these methods. The fossil record is like a movie with most of the frames cut out. Because it is so incomplete, it can be difficult to establish exactly when particular evolutionary changes happened.
Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. Confounding factors rack up for species that are very distantly related, making the earlier dates more uncertain.
These difficulties mean that the dates in the timeline should be taken as approximate. As a general rule, they become more uncertain the further back along the geological timescale we look. Dates that are very uncertain are marked with a question mark.
Answer:
<h2>Its true!!</h2>
Explanation:
Actually the haemoglobin molecule consists of 2 parts, the haem which is a prosthetic group and the other globin which is a protein. So the haemoglobin as is a protein so, is arranged in quaternary structure of protein which contains 4 subunits. The subunits depend upon the organism whose haemoglobin is being talked about. So the normal haemoglobin found in red blood cells contains 2 alpha subunits + 2 beta subunits. At the centre of each subunit there is the haem part attached. To the centre of haem the Fe3+ ion are present which actually attaches to 1 Oxygen molecule. So as 4 subunits are present and each subunit has 1 Fe3+ ion, so total 4 Oxygen molecules can bind to the 1 Hb molecule!!
Answer:
Check for chloroplasts for a plant cell and look for mitochondria's for an animal cell
One of the plants in this grouping are chrysanthemums.
