Archivo

13e Population growth.

A population is a group of the animals or plants living in the same habitat e.g. greenfly on a rose bush or daisies in a lawn or a shoal of herring in the sea...

a. Writedown some more animal and plant population and the habitat they live in
b. Why do you think that animals and plant live together in populations?
Think about what they need for survival and howthey keep up their numbers

How do populations grow?
Simon put some yeast into sugar solution. It soon starred to grow.
Every half hour he looked and drop of the yeast under the microscope. Hecounted the number of cells he could see and recorder it in table.

Then he drew a graph like the growth curve shown here:

What do you think happended to the number of yeast cells

i) in the firstfew hours? ii) laterin the experiment? and
iii) at the end of the experiment?

Why do you think the population of yeast cells stopped growing?

When yeast grow one cell divides into 2. Then 2become 4. Then 4 become 8, 16, 32, 64 and so on.

Form Simon’s experiment you can see the some population grow very fast. So why isn’t the earth over-run with animals and plants?
The answer is thatnot all of them survive.
Some factors limit the population growth. For example.

* light * overcrowding * food and water * disease
* climate * predators * oxygen * shelter

> Copy and fill inthe table for each factor above.

Factor How the factor can limit population size
*light * lack of light slows growth of plants

a) What area of knowledge does this textbelong to?
El crecimiento de la población.
¿Cómo crecen las poblaciones?

b) What visual elements does the author use?
Imágenes que representan las células.

c) Which words are repeated?Población, factores, crecimiento, células.

d) Based on the repeated words, what is the main subject of the text?
El crecimiento de la población.

A population is a group of animals or plants...