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5. Cause and effect

We have now established that changes do not occur at random – one change brings about another. You probably know the concept of cause and effect. At this stage it should be great fun to think and chat about cause and effect. Argumentation is nothing new to you; after all, you are in Grade 7!

Activity 5:

To choose the best options with regard to population changes

[lo 3.2]

CHOOSE THE BEST OPTION

Underline the correct answer from the words in brackets:

1. As the fertility in any community increases, the births in that community will (decrease/increase).

2. Good medical care for the entire community normally leads to a drop in the (death rate/life expectancy).

3. If the mortality rate in a [primitive] society is very high, the birth rate will definitely be (high/low).

4. When any society is used to receiving state benefits for the aged, families will tend to get (smaller/bigger).

5. A population with a high fertility rate and a low mortality rate, will (shrink/grow).

6. The population of any country that is severely affected by the Aids-pandemic, will experience a drop in (fertility/life expectancy).

At the moment the developing countries are experiencing a rapid growth in their population, so that the population pyramid in each case shows a typically young population. Developed countries , such as almost all of the European states, the USA and Canada, once experienced times when the population could be described as young. These states have since undergone demographic change.

6. Demographic change, and how it can be represented by means of population pyramids

Here we have a description (a history in a certain sense) of the population structure of England and Wales. This is a good example of the different stages through which a population progresses.

Population pyramids

Over the centuries the population has remained relatively constant. The birth as well as the mortality rate was high, and the life expectancy short. The pyramid of this group probably resembled the one in Figure 1(a) at the beginning of this learning unit.

  1. After the changes effected by the agricultural and industrial revolutions when farms started to produce more food due to mechanisation, and people turned to factory jobs for an income, the population showed a marked growth. The birth rate gradually started to overtake the mortality rate because of better nutrition, improved medical care, and better sanitation. As before, families were still quite large, but as fewer babies and youths died, the total population took on a “young” character.
  2. Fifty years later the population pyramid showed a marked difference from the previous pyramid. A lower fertility rate then caused the younger part of the population to shrink proportionally. The lower fertility rate was due to the fact that women were prepared and chose to have fewer children, as they preferred to join the workforce to help earn an extra income for their families. Moreover, the state took on the responsibility of caring for the aged, which meant that they were no longer dependent on their children. (In earlier times children were regarded as an “insurance policy for old age”.)

Questions & Answers

calculate molarity of NaOH solution when 25.0ml of NaOH titrated with 27.2ml of 0.2m H2SO4
Gasin Reply
what's Thermochemistry
rhoda Reply
the study of the heat energy which is associated with chemical reactions
Kaddija
How was CH4 and o2 was able to produce (Co2)and (H2o
Edafe Reply
explain please
Victory
First twenty elements with their valences
Martine Reply
what is chemistry
asue Reply
what is atom
asue
what is the best way to define periodic table for jamb
Damilola Reply
what is the change of matter from one state to another
Elijah Reply
what is isolation of organic compounds
IKyernum Reply
what is atomic radius
ThankGod Reply
Read Chapter 6, section 5
Dr
Read Chapter 6, section 5
Kareem
Atomic radius is the radius of the atom and is also called the orbital radius
Kareem
atomic radius is the distance between the nucleus of an atom and its valence shell
Amos
Read Chapter 6, section 5
paulino
Bohr's model of the theory atom
Ayom Reply
is there a question?
Dr
when a gas is compressed why it becomes hot?
ATOMIC
It has no oxygen then
Goldyei
read the chapter on thermochemistry...the sections on "PV" work and the First Law of Thermodynamics should help..
Dr
Which element react with water
Mukthar Reply
Mgo
Ibeh
an increase in the pressure of a gas results in the decrease of its
Valentina Reply
definition of the periodic table
Cosmos Reply
What is the lkenes
Da Reply
what were atoms composed of?
Moses Reply
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Source:  OpenStax, Geography grade 7. OpenStax CNX. Sep 09, 2009 Download for free at http://cnx.org/content/col11021/1.1
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