Everything Life Sciences Grade 10

FACT

Natural selection is
a process you will
learn about in more
detail in Grades 11
and 12.

FACT
WATCH: This
explains how
natural selection
takes place!
See video:
SHORTCODEat
http://www.everythingscience.co.za

Atlantic and Indian Oceans.

Figure 11.3: Diagram showing continental drift.

Natural selection DUMMY

Through a process known asnatural selection, adaptations that allow one organism to sur-

vive better than another and produce more off-spring, results in future generations of or-

ganisms who have acquired those traits. For Grade 10, you are required to understand the

following key features of evolution by natural selection:

• Individuals in a species show a wide range of variation: .e.g. the many different types
  of dogs you see.


• The variation is caused by genetic differences.


• Individuals that are well-adapted to the environment in which they live are more likely
  to survive and produce more offspring.


• The genes that allowed the individuals to be successful are passed on to the offspring
  in the next generation.


• Over many hundreds (and thousands) of generations this results in changes in the
  physical appearance and habits of organisms.

Fossil formation DUMMY

Thefossil recordis a key source of evidence through which our understanding of Earth’s

history has developed.

Fossils are the remains of animals or plants from the remote past preserved in its originally

buried form (petrified form) or as mold or cast in rock. Generally, a preserved specimen is

regarded as a fossil if it is older than approximately 10 000 years (although this is not a strict

definition).

Fossils are considered to be remnant of an organism of a past geological era. Examples of

318 11.2. Representations of life’s history