7.1 How it all began

• Biologie
• biology
• Middelbare school
• vwo
• Leerjaar 3

Who is this man?

00:55

what are the two basic ideas of Darwin's evolution?

Put the events of Darwins life in the correct order. You can use your book!

Trip with the HMS beagle

Noticed diverstity

Visited Galapagos

Concluded species change

Darwin arrived back in England

Published 'the origin of species'

What do you need for Natural Selection

1. To be the biggest
2. To be unique
3. Being able to pass on genes
4. To adapt when you're still alive

natural selection 

--> every individual is unique (no clones)

--> differences in traits  are inheritable 

(Heredity) 

---> 1.  differences in inheritable traits 

i.e. there are green and brown beetles 

What will happen to the beetle population, when a bird comes by that only eats green beetles?

1. There will be more brown beetles
2. There will be more green beetles
3. The beetle population will stay the same
4. The beetle population will go extinct

green beetles tend to get eaten by birds and 

survive to reproduce less often than brown beetles

and surviving brown beetles have brown baby

beetles 

the more advantageous brown colouration which allows the brown beetle to have more offspring becomes more common in the beetle population. 

If this process continues, eventually, all individuals in the population will be brown 

--> Differential reproduction

fernandina

-> small fruit

santiago/san salvador

--> small seed

santa cruz

--> worms

pinta

--> large fruit

fernandina

-> small fruit

santiago/san salvador

--> small seed

santa cruz

--> worms

pinta

--> large fruit

Which finch belongs to which island?

fernandina

-> small fruit

santiago/san salvador

--> small seed

santa cruz

--> worms

pinta

--> large fruit

homework

Read Paragraph 7.1 and make the questions in your book

pedigrees

Healthy male

Healthy female

Male/female with genetic abnormality

Is this condition dominant or recessive?

1. dominant
2. recessive

What do you remember?

Gene, allele, dominant, recessive, genotype, phenotype, homozygous, heterozygous

Gene

The part of a chromosome that determines a trait, like eye colour

Allele

Different forms of the same gene. Like brown, green and blue eye colour.

Dominant

The allele that is expressed

Recessive

The allele that is not expressed, only when two of these are paired, are they expressed

Genotype

Your inherited genetic characteristics. 

Phenotype

How your inhereted characteristics are represented. So eye colour, hight, blood type and more. 

Homozygous

Two of the same alleles. 

Heterozygous

Two different alleles.

Let's practice

In mussels, brown coloring (B) is dominant, and blue coloring (b) is recessive. 

A homozygous brown mussel crosses with a blue mussel.

What percentage of offspring are expected to be brown?
0%, 25%, 50%, 75% or 100%?

One more

Assignment

1. Practice the monohybrid crossing with a punnett square

Websites to practice with:
Youtube - Amoeba Sisters:  Monohybrids and the Punnett Square Guinea Pigs
Khan Academy - Monohybrid punnett squares (practice)
Assignment 23, 24, 25, 26 and 27, 28 and 29 of your workbook

Done? Make your summary of paragraph 5.4

Discussion about the questions allowed.

Need help?

Ask the teachter