Lesson 7: Comparing skeletons part 2

• Biologie
• Middelbare school
• vwo
• Leerjaar 1

Get ready:

-lessonup

-notes

Today: 

Comparing skeletons part 2

       -Evironment & Time

Worksheet comparing homologous structures

3. Environment

Water animals: 

-Body shape in water

-Streamlined body 

- minimize resistance from water

-Short and wide limbs

4. Time

-Skeletons change over time

-how bones are shaped can tell us something about the past

Vestigial organs: 

Organs that an animal has but doesn't use 

Example:  Tail bone 

Example:
Pelvis/Femur in whale 

Vestigial organ with no function:

Evolution of whales

Leg bones in snakes -> Tickle females during mating

Vestigial organ with new function

Why are there not so many early fossils?

1. Early forms of life were soft bodied organisms
2. No animals were living a long time ago
3. Bones of those animals were never found
4. What are fossils again?

Which one is not an example of how fossils form?

1. When parts of organisms have not been decayed
2. Parts of organisms are slowly replaced by minerals during the decay process
3. Preserved traces of animals such as footprints
4. Animal bones are non-living and always remain in the earth surface

When is a species extinct?

1. When a group of animals of that species dies
2. When all animals of that species died

Discussion of Worksheet 

Question 1: 

Write at least two sentences describing what you already know about homologous structures?

The bones of the hand

The bones of the arm

Question 2

The next lesson: 

-Owl ball dissection 

Work further on the worksheet 

-comparing homologous structures

-Question 3 to 9 

HW for next lesson

-Finish the worksheet 'comparing homologous structures'

-Prepare for the owl dissection lab