Everything Life Sciences Grade 10

• It takes special circumstances for fossils to form, and fossils can be dated by radiometric
  dating.


• Climate and geography helped shape the evolution of life on Earth.


• Geological timescales are divided into eons, eras and periods.


• The Cambrian explosion, was a rapid explosion in the diversity of life-forms. All animal
  groups have their origin in the Cambrian explosion.


• During the Paleozoic the first fish, animals with shells and insects evolved and plants
  first colonised land.


• The Mesozoic was the ‘age of dinosaurs’, later in the era birds evolved, and gym-
  nosperms evolved.


• The Cenozoic is the most recent era and was the ‘age of mammals’.


• Mass extinctions are massive losses in life, and there have been five mass extinction
  events in history.


• In the last 4 million years significant changes have occurred in species occurring in
  Africa, including the evolution of humans.


• Humans have a massive effect on biodiversity and the natural environment and are
  partially responsible for the ’6th mass extinction’.


• South Africa is rich in many fossils from diverse time periods.


• Fossil tourism is a source of income and employment in fossil localities.

Exercise 11 – 1: End of chapter exercises

1. In each of the following cases write down the letter of the most correct alternative.
   a) Which of the fossils have been found in Namibia?
   i. Mammal-like reptiles
   ii.Glassopterisleaves
   iii. Soft-bodied animals
   iv. Early mammals
   b) What was the importance of stromatalites
   i. They released oxygen into the air
   ii. They absorbed oxygen and prevented animals getting poisoned
   iii. They are the closest ancestors of modern plants
   iv. They were algae trapped in sediment
   c) A problem in determining the accuracy of radiometric dating is that
   i. scientists are not sure that radioactive decay actually occurs
   ii. the decay rate of minerals can change without warning
   iii. the rocks that contain the fossils can’t be dated
   iv. only organic samples can be dated radiometrically


2. Essay:
   
   
   • The Cradle of Humankind World Heritage site has numerous tourism and eco-
     tourism attractions. These ecotourism attractions include the Sterkfontein Caves,
     the Wonder Caves, the first gold mine in Gauteng, rock art sited and as many
     game reserves.
   
   
   • You are to write an essay of approximately 1 to 1
   
   
   
   

1

2

pages promoting one of these

336 11.7. Summary