15. a) Describe a hormone
a) Explain why the pituitary gland is also called the master gland
b) Distinguish between endocrine and exocrine glands
(0) Name one gland which is both an endocrine and exoc
c) Explain how the body increases its level of glucose before the start of a race.
16. Touching a hot object brings about a reflex response.
(a) Why is such a response important to the body?
(b) Explain how a nerve impulse passes from one neuron to another.
© A possible risk of danger to the body can bring about the release of the hormone a
How does this hormone prepare the body to deal with danger?
d) State two differences between the nervous system and the hormonal system

[a]The main endocrine gland. It is a small structure in the head. It is called the master gland because it produces hormones that control other glands and many body functions including growth. The pituitary consists of the anterior and posterior pituitary.

[b]Endocrine glands release chemical substances directly into the bloodstream or tissues of the body. The chemical substances released by the endocrine glands are known as hormones. Exocrine glands release chemical substances through ducts to outside the body or onto another surface within the body.      The liver and pancreas are both exocrine and endocrine glands

[c]adrenal gland

[a]A reflex action is an automatic (involuntary) and rapid response to a stimulus, which minimises any damage to the body from potentially harmful conditions, such as touching something hot. Reflex actions are therefore essential to the survival of many organisms.

[b]When a nerve impulse reaches the end of an axon, the axon releases chemicals called neurotransmitters. Neurotransmitters travel across the synapse between the axon and the dendrite of the next neuron. ... The binding allows the nerve impulse to travel through the receiving neuron.

[c]Adrenaline is a hormone released from the adrenal glands and its major action

[d]One of the significant difference between the nervous system and endocrine system is that the nervous system uses electrical impulses to send messages through neurons while endocrine glands use hormones to send messages to the target cells through the bloodstream.

Explanation:

from almost the creation of the first true maps of the earth, people started seeing how continents would be able to fit together.   in particular, people noticed that south america fits almost exactly into africa.

you should be aware that while world maps were around early in the 1600’s and better defined by the end of the 1700’s, those maps were not ‘public’ but were treated as state secrets.   and so it was not till much later that the broader ‘science’ community had access to good quality and accurate world maps.

get the whole story here…

it is now known that most of the major continental masses can be fit together in a jigsaw process.   in fact we now know that the continents were indeed once all joined together as one land mass – the supercontinent of pangaea.

if you look at most world maps you will ponder how this is evidence, as the continents really don’t appear to ‘fit’ together very well.   what you need to understand is that the vast majority of maps are drawn using a map projection that has the north and south poles (which are points) are a line the width of the map at the top and bottom.   this means that the map distorts the true shape of the earth’s land and oceans as you love closer to the poles.     some other map projections distort less, but have the map shape looking like segments of an orange.   see here for a range of map projections.   check out the way greenland changes size in each!

what is more remarkable, is the next piece of evidence when added to the shape of continents.

location of mountains and fossils

what is remarkable, when you reassemble all the continents together, the ancient mountain ranges (many now eroded to their cores) and the location of rock types and fossils all match up.