Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Biodiversity is the measure of the number and variety of species in a certain area.
Biodiversity is highest nearer the equator and lower nearer the poles.
Global biodiversity is the total number of species on the planet, for which values are only
estimates because not all species have been discovered for example tropical rainforests
are largely unexplored.
Species is a group of similar organisms that are able to reproduce to give fertile
Habitat is the area inhabited by a species.…read more

Page 3

Preview of page 3

Here's a taster:

Increase in human population puts strain on resources and space to live, leading to
industrialisation, destroying habitats and food sources, for example by deforestation.
Pollution causes a decrease in biodiversity.
Over-harvesting of food sources such as fish decreases biodiversity, for example cod
has become endangered from over-harvesting.…read more

Page 4

Preview of page 4

Here's a taster:

Ex situ conservation is when a species is protected by moving it from its natural habitat,
for example relocating them to a safer area, breeding schemes in captivity,
development of botanic gardens, and creating seed banks (freezing seeds of plants).…read more

Page 5

Preview of page 5

Here's a taster:

Being adapted to an environment means an organism has features that increase its
chances of survival and reproduction, and because the desirable genes are passed on,
the chances of the offspring reproducing successfully are also increased.
Behavioural adaptations are ways organisms act that increase the chance of their survival
such as possums `playing dead'.…read more

Page 6

Preview of page 6

Here's a taster:

Darwin explained these observations by saying individuals within a population show
variation in their phenotypes (characteristics), predation, disease and competition create
a struggle for survival, better adaptations are more likely to survive, reproduce and pass
on their advantageous adaptations to their offspring, so over time the number of
individuals with the advantageous adaptations increases and over generations this leads
to evolution as the favourable adaptations become more common.…read more

Page 7

Preview of page 7

Here's a taster:

DNA evidence can be used to show evolution, as evolution is the gradual change in the
base sequences of an organisms DNA, and because species are more closely related the
more recently they diverged, organisms that diverged more recently should have more
similar DNA, for example humans and chimps diverged fairly recently so the DNA base
sequence is very similar, and much more similar than that of humans and mice, as these
species diverged a long time ago.…read more

Page 8

Preview of page 8

Here's a taster:

Classification groups similar organisms together to make them easier to identify and
Taxonomy is the study of classification.
There are seven taxonomical groups; kingdom, phylum, class, order, family, genus.
Organisms in the same genus are often very similar but are different species because
they can't breed together to give fertile offspring.
Phylogenetics is the study of the evolutionary history of species.…read more

Page 9

Preview of page 9

Here's a taster:

Respiratory system
The lungs are found in the thorax, and are specialised for gas exchange.
Gas exchange is the absorption of oxygen into the blood, and carbon dioxide out of the
blood into the lungs.
Gas exchange takes place in the alveoli, which have a squamous epithelium layer one cell
thick, and are arranged in bunches at the end of bronchioles, surrounded by a network of
capillaries so each alveolus has its own blood supply.…read more

Page 10

Preview of page 10

Here's a taster:

The bronchi have smaller pieces of cartilage, smooth muscle, elastic fibres, goblet cells
and a ciliated epithelium.
The bronchioles have no cartilage and the alveoli have no cartilage, no smooth muscle, no
goblet cells, elastic fibres and a squamous epithelium.
Pleural fluid is found between the lungs and the lining of the thorax, and acts as a
lubricant, preventing friction during breathing.
Surfactant covers the surface of the alveoli to reduce surface tension and prevent the
alveoli collapsing when expiring.…read more


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »