Biology - Chapter 11 - Biodiversity

Define the following terms: Population, community, species, habitat, ecosystem and biodiversity

Population - Individuals of the same species

Community - All living organisms in a habitat or ecosystem

Species - Organisms that can interbreed, creating fertile offspring

Habitat - Where an organism lives

Ecosystem - Interaction of all biotic and abiotic factors in an area

Biodiversity - The variety of organisms living in an area

What is habitat diversity?

One of three types of diversity, consisting the different number of habitats within an ecosystem

What is species richness and evenness?

Richness: Number of different species in a habitat

Evenness: Distribution of the number of individuals by species

What is genetic diversity?

Variation of alleles by species

What do these methods of gathering individuals involve: pooter, nets, pitfall traps, kick sampling, tree beating?

Pooter - Mouth goes around one tube and draws in insects through the other tube

Nets - Put in water, along the ground or in the air to capture anything moving that can’t be grabbed

Pitfall traps - A dug hole insects will fall into (too deep to let them crawl out, must be covered on top to prevent rain accumulating)

Kick sampling - Kicking a river bed to disturb it, using a net to capture downstream-flowing organisms

Tree beating - Placing a large white cloth under a tree and shaking organisms out

What are the genetic definitions you need to know to understand genetic biodiversity?

Genotype - Two alleles present which determine phenotype

Phenotype - Expression of characteristics based on the genotype

Homozygous - Two identical alleles of one gene are inherited

Heterozygous - Two different alleles of the same gene are inherited

Allele - A variation of the gene coding for a trait’s expression

Chromosome - Coiled strands containing DNA

What is a polymorphic and monomorphic locus?

At a point (locus) where the gene has one allele (mono) or more than one (poly)

How do you calculate the proportion of polymorphic gene loci? What should you express it as unless otherwise stated?

Number of polymorphic gene loci/Total number of loci, expressing as a decimal

What is the gene pool?

The variety of genes present in a habitat, community or ecosystem

Which actions decrease the gene pool?

• Selective breeding as undesired alleles go

• Captive breeding due to limited numbers

• Natural selection - extinction decreases the gene pool

• Founder effect - Migration of organisms will cause limited alleles in the migrating population

• Genetic drift - If reproduction means an allele doesn’t pass on, said allele can die out

• Plant monoculture - Only growing one type of crop reduces variation

Which human factors decrease biodiversity?

• Habitat loss

• Herbicides and pesticides

• Overexploitation (of land)

• Species loss

• Pollution

• Urbanisation (reduces habitats)

What is the effect of human impact on forests?

• Wildfires are 90% caused by us in hot, dry weather

• Palm tree destruction reduces biodiversity and promotes monoculture

• Clearing land for a variety of things (food, building, farming, wood, infrastructure and settlement) forces animals to migrate

How does agriculture impact the environment?

• Making space for crops and machines

• Herbicides and pesticides reduce biodiversity

• Monoculture

How does climate change affect biodiversity?

• Temperature fluctuation

• Climate fluctuation

• Habitable status changes - can become more or less habitable

• Biodiversity up/down

• Need for animals to migrate causes shift, being unable to migrate can cause extinction

What reasons do we have, economically and aesthetically, to retain biodiversity?

Economic: Reducing soil depletion as less nutrients mean more costs for herbicides/pesticides

Aesthetic: Keeping landscapes promotes tourism

What ecological reasons do we have?

• Predator-prey numbers can fluctuate if THEIR predators or prey die out

• Keystone species (those with a large impact on their environment) can cause a lot of disruption if they fluctuate

• Minimising disruption to food and nutrient cycles

• Resource use from these organisms