BIOLOGY

UNIT 3&4

UNIT

3

Topic

1

Describe genetic, species and ecosystem diversity.

Genetic diversity - Variety of genetic information of species or population such as different alleles and genes.

species - The number, abundance, and proportion of various species within a specific location.

Ecosystem diversity - diverse range of habitats, ecological processes, and community among ecosystems.

distinguish between abiotic and biotic

Abiotic: The non-living physical factors within an environment that affect an organisms ability to survive.

Biotic: The living components of an ecosystem.

Describe the biological species concept and identify its limitations.

• Considers a type of species as a type of organism in a group by being fertile its ability to breed and produce viable offsprings with another organism that is part of the group and not with an organism from another group.

limitations:

• geographical isolation - physical barrier/climate prevents two different groups from breeding

• Asexual organisms - cannot breed due to cloning

• fossil species - extinct so they can not breed

• different mating seasons

 Identify the major taxa in the Linnaean system of biological classification and explain how it is used to classify and name species.

the major taxa include:

• Domain

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

Explain how the Linnaean system is used to classify and name species

• Grouping based on shared physical/behaviour structures

• uses the Binomial Nomenclature for scientific naming.

How to write Binomial Nomenclature

• must be all underlined

• first letter of name in capitals

How to calculate estimated population? state formula and what each means

• Lincoln index

• (𝑁 = M x n/𝑚 )

• (N) = Total population estimate;

• (M) = Number initially caught and marked;

• (n) = Total number caught in the second sample;

• (m) = Number of marked individuals recaptured.

What 4 assumptions hold the Lincoln index to true for the data to be valid?

1. The population is closed (no births, deaths, immigration, or emigration between samples).

2. The marks/tags do not fall off or fade.

3. The marks do not affect the survival or behavior of the animal (e.g., making them easier for predators to see).

4. Marked animals mix completely back into the population before resampling

what formula is used to for the absolute count of different species present in an ecosystem? what does each term mean

• Species richness

• S = s/square root n

• S: The Species Richness Index (the final calculated value representing the variety of species adjusted for sample size).

• s: The total number of different species recorded in your sample.

• N: The total number of individual organisms (of all species combined) in your sample.

What formula is used to evaluate how evenly distributed the overall community?

• Species Evenness (Relative abundance): Ts/Tp x 100

• Ts = The number of individuals found in one specific species

• Tp = The total number of individuals across all species combined in the sample area

What is Percentage Frequency and its formula? What is percentage cover?

What formula is used to compare biodiversity? What does each term mean? Interpret what the values mean.

• Measures the probability (\(0\) to \(1\)) that two randomly selected individuals from a sample belong to different species.

• Closer to 1 = High diversity (highly stable ecosystem).

• Closer to 0 = Low diversity (dominated by few species, vulnerable to change).

Distinguish between Random, Systematic, and Stratified sampling.

Random Distribution – An unpredicted spacing of individuals, where the position of each individual of a species is independent of the other individual of the species in a given environment.

Uniform – Individuals are more or less equally spaced throughout the entire area.

Clumping – Individuals are found clustered in groups in particular parts of the habitat. Most common pattern of distribution of plants and animals in nature.

Quadrats vs. Line Transects

• Quadrats: A defined area (usually square) with a fixed size, used to count organisms within a area.

• Transect: A line often laid across a ecological gradient, along which abundance of organism is recorded either within the whole area or at specified intervals.

 

Minimising Bias (Data Integrity) — What are 4 strategies used to ensure data reliability?

1. Size and number of samples: Maximising sample size minimizes the impact of data anomalies.

2. Random-number generators: Establishes coordinate mapping grid lines to remove human selection bias.

3. Counting criteria: Rigid rules (e.g., "only count a plant if it is more than 50% inside the quadrat").

4. Calibrating equipment: Ensuring electronic data-loggers are calibrated to zero to ensure precision.

Spatial Distribution Patterns — Name the 3 types and identify which pattern makes random sampling unreliable.

• Types: Uniform, Random, Clumped.

• Unreliable: Clumped distributions heavily impact data validity. Random quadrats will either hit an entire clump (overestimating population) or miss them completely (underestimating population), making stratified sampling a necessity.

Microhabitats — Define the term and describe its impact on species distribution.

• A small, localized, specialized habitat within a larger ecosystem (e.g., the space underneath a rotting log).

• It creates micro-climatic variations (e.g., higher humidity, less light) which force species into clumped or restricted distributions.

Describe how the distribution and abundance of species in an ecosystem are influenced by biotic and abiotic factors

• biotic factors — food availability, competition for resources, predation, disease

• abiotic factors — space, shelter, availability of water, nutrients, environmental conditions.

• increase/decrease extinction, survival, access to food

Specht’s Vegetation Classification System — What 2 metrics are used to classify an ecosystem?

1. The growth form/structural type of the tallest dominant stratum (e.g., trees, shrubs, herbs).

2. The percentage foliage cover of that tallest canopy layer (e.g., Dense: 70-100%, Mid-dense: 30-70%, Sparse: 10-30%. Open <10%..

• Holdridge Life Zone Classification Scheme — What 3 environmental parameters are used to classify an area?

• View digital triangle table for visual reference

1. Mean Annual Biotemperature (on a logarithmic scale).

2. Annual Precipitation.

3. Potential Evapotranspiration (PET) Ratio.

Modes of Population Growth — Contrast Exponential vs. Logistic Growth

• Exponential (J-curve): Unlimited population growth occurring under ideal conditions with infinite resources.

• Logistic (S-curve): Initial growth that slows down and levels off when it encounters environmental resistance at the carrying capacity (\(K\)).

r-strategists vs. K-strategists — Contrast their growth curves, environments, and reproductive outputs.

• r-strategists: J-curve growth; unstable/unpredictable environments; small body size; massive numbers of offspring; short lifespan; zero parental care. e.g rabbit.

• K-strategists: S-curve growth; stable/predictable environments; large body size; very few offspring; long lifespan; high parental care investment (e.g humans and elephants.

State the population change formula and population growth rate formula.

r = (b + i) - (d + e)

• r = growth rate

• b=births

• i= immigration

• d=deaths

• e=emigration

How to calculate population density?

• D= population size/ size of area

Stimuli/figures