1
state the problem
<span></span>2
hypothess (prediction)
<span></span>3
design the experiment
<span></span>4
record and analyze the date
<span></span>5
<span>conclusion (what did you learn)</span>
Hormones are a group of chemicals released by exocrine glands
These hormones are directly secreted into bloodstream from where they reach the site.
<span>If
ever your small boat capsizes in the swift water, all you need to do is to float
on the upstream side of the craft and never try to walk in swift water nor
stand, and this will assure your safety. Also make your feet arms widely opened
or extended with your feet pointed to the downstream.</span>
Answer:
Watson and Crick proposed the double helical model of DNA.
Explanation:
- This model says that DNA exist as double helix. It has two polynucelotide strands running in opposite direction i.e the strands are anti-parallel.
- Each polynucleotide strand is made up of several nucleotide liknked together by phophodiester bonds.
- The two strands are not coiled upon each other but the double strand is coiled upon itself around a common axis like the spiral stair case. Here base pairs forms the stairs and backbone of two strands form railing. Back bone contains sugar and phosphate.
- The base pairing is specific, adenine always pairs with thymine and guanine always pairs with cytosine. Thus if we see any base pair, it consists of one purine and one pyrimidine.
- The two strands of DNA thus show complementary base pairing.
- The strands are held together because of hydrogen bonding between the bases in opposite strand.
- One full helical turn involves ten base pairs and the base pairs are stacked 3.4 A apart.
- This form is called as B-form of DNA.
The number of mitochondria per cell varies widely; for example, in humans, erythrocytes (red blood cells) do not contain any mitochondria, whereas liver cells and muscle cells may contain hundreds or even thousands. The only eukaryotic organism known to lack mitochondria is the oxymonad Monocercomonoides species.
