Grade 9 Science
Performance Based Assessment
Unit One: Biological Diversity
Part 1: How to Calculate Biodiversity Index
Show Your Understanding of the Following…
The question of how many different species exist in a particular environment is central
to the understanding of why it is important to promote and preserve species diversity. A
uniform population of a single species of plants adapted to a particular environment is
more at risk if environmental changes occur. A more diverse population consisting of
many species of plants has a better chance of including individuals that might be able to
adapt to changes in the environment.
Scientists use a formula called the diversity index to describe the amount of species
diversity in a given area. A simple biodiversity index is calculated as follows:
number of runs (numerator)
=
total number of specimens (denominator)
diversity index
number of runs – the number of different species in the area
total number of specimens – total number of individuals in the area
Example #1:
A 4X4 meter square area in a carrot patch has 300 carrot plant, all the same species. It
has a very low biodiversity index of 1/300 or 0.003.
1 ÷ 3 = 0.003
Example #2:
A 4X4 meter square area in the forest has 1 pine tree, 1 fern, 1 conifer tree, 1 moss and
1 lichen, for a total of 5 different species and 5 individuals. The biodiversity here is high.
5÷5=1
Try these questions…
What would be the biodiversity index of the following areas if each symbol resembled a
different species?
Area 1
⌂⌂⌂□□◄◄◄◄☼☼☼☼☼▲
Area 2
♠♠♠♠♣♣♀♀♀♀♥♥♥○◙◙♂♂♂♂♂☺☺
** Always Show Your Work – Formula, Substitution and Answer **
Think: Is this the best way to determine biodiversity in an ecosystem?
Key Words to Know
1. Biological Diversity
- the wide range of number and variety of organisms living in an area
- biodiversity exists due to the wide range and variety of species living in
our world
- biological diversity if important for the health and survival of many
communities
- scientists still have a lot to learn about how different members in natural
communities affect each other
- in our world there is a wealth of biodiversity
- interactions among different species is important for every living
organisms
- species of out plant are not distributed evenly
- equatorial regions have the greatest biological diversity
- protecting biological diversity is important for all living organisms
2. Species
- species are a group of organisms that share similar genetic and physical
characteristics
- organisms are grouped together as a species if they interbreed in nature
and produce fertile offspring
3. Variation
- variation in life makes up the Earth’s biological diversity
- variation is differences in characteristics caused by genetic (nature) and
environmental factors (nurture)
- variation is important both within a species and between different species
- this helps to ensure that some individuals will survive in a changing
environment and to limit competition for resources
Check for Understanding…
Part 2: Understanding the Difference Between Mitosis and Meiosis
Comparing Mitosis and Meiosis
Mitosis
Check for Understanding…
Meiosis
Part 3: Punnett Squares
How to Use Punnett Squares
Punnett Squares are a useful tool to determine the probability of inheriting a specific
trait. It may seem confusing at the start, but review over the genetic terminology and it
will begin to make sense. Punnett Squares are somewhat similar to a times table chart.
There are only three basic combinations possible for Punnett Squares.
* Remember the difference between homozygous and heterozygous.
Homozygous

when an organism has a pair of identical alleles for a character, they are said to
be homozygous for that characteristic (PP, pp)
Heterozygous

when an organism has two different alleles for a gene (Pp) they are said to be
heterozygous for that characteristic.
Combination #1: Homozygous (dominant) crossed with Homozygous (recessive)
D
D
d
Dd
Dd
d
Dd
Dd
This punnett square shows that all offspring will be heterozygous for the dominant trait.
Combination #2: Homozygous (dominant or recessive) crossed with
heterozygous.
D
D
D
DD
DD
d
Dd
Dd
OR
d
d
D
Dd
Dd
d
dd
dd
This punnett square shows that all offspring has a 50% chance of being heterozygous
dominant trait or homozygous for whatever trait was crossed (dominant or recessive).
Combination #3: Heterozygous crossed with heterozygous.
D
d
D
DD
Dd
d
Dd
dd
This punnett square shows that all offspring has a 50% chance of being heterozygous,
25% being homozygous dominant and 25% chance of being homozygous recessive.
Check for Understanding…
Part 4: The Chemical Make-up of DNA – The Structure
The Structure of DNA
DNA has the structure of a ___________________________. Also called the
______________________________.
The sides of the ladder are made up of units of _____________________ and
________________________.
The rungs are made up in pairs of ________________________ bases that occur in
four different forms: _____________________ ( ), _______________________ ( ),
_________________________ ( ) and ________________________ ( ). The
nitrogen bases are like pieces of a puzzle and only certain pieces fit together.
Pairs are as follows:
____________________ and ____________________
____________________ and ____________________
Check for Understanding…
Part 5: Identify the Effects of Human Impacts on Ecosystems
Review over information found in Topics 7 and 8.
1. How have human actions impacted the survival of species?
- review concepts in Topic 7 – The Sixth Extinction?
- understand the meaning of extinction and extirpation
- causes of extinction and extirpation (human actions)
2. What challenges/solutions have humans taken in order to preserve biological
diversity locally and globally?
- review concepts in Topic 8 – Pains and Gains
- evaluate the successes and failures of protecting biodiversity
- roles of zoos
- development of seed banks
- establishing protected areas (National Parks/Natural Preserves)
- international treaties - purpose
- wildlife trade regulations
Check for Understanding…