With a ruler, draw a line that is 20 cm long. Divide the line into five, 4-cm segments. On a scale of each segment representing one billion years, label the following events in the history of Earth: a. formation of the earth
b. origin of life
c. evolution of photosynthesis
d. evolution of eukaryotes
e. evolution of multi-cellular life
f. the Cambrian explosion
g. first vertebrate land animals
h. evolution of dinosaurs
i. evolution of human beings

Solution:

The first traces of the life that existed on the earth can be traced back to about as old as 4.2 billion years. It indicates that life has evolved around 200 million years ago after the first appearance of the liquid water.

The origin of the life on earth is a natural process and is a series of evolution what we see today. Firstly earth was formed by dust and smoke particles and then different forms of life began to evolved on the earth.

The events of the evolution in the history of the earth is shown on the following number line below :

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c

after receiving a stimus, the sensory receptors send(s) signals to the appropriate area of the body.  

the must be sensory neurons.  

hope its .