genes cells and tissues revicion pack uni

Define biodiversity and its three levels.

Biodiversity is the variety of life and is measured at three levels: genetic diversity, species diversity, and ecosystem diversity.

What is genetic diversity and why is it important?

Genetic diversity refers to the variety of genes within a species. It enables populations to adapt to changing environments.

What is species diversity and what challenges arise when measuring it?

Species diversity is the number and abundance of species in a region. It's hard to measure due to cryptic species and unclear species definitions.

How is ecosystem diversity defined?

Ecosystem diversity refers to the variety of habitats, communities, and ecological processes in the biosphere

What factors threaten biodiversity?

Habitat loss, pollution, climate change, invasive species, and overexploitation

What is a keystone species? Give an example.

A species that has a major role in maintaining ecosystem structure. Example: Sea otters controlling sea urchin populations.

How do ecosystem engineers affect biodiversity?

They create or modify habitats, supporting other species. Example: Beavers building dams.

What is the 6th mass extinction event and what causes it?

Current rapid species loss due to human activity such as habitat destruction and pollution.

What is species diversity and what challenges arise when measuring it?

Species diversity is the number and abundance of species in a region. It's hard to measure due to cryptic species and unclear species definitions

How is ecosystem diversity defined?

Ecosystem diversity refers to the variety of habitats, communities, and ecological processes in the biosphere.

What factors threaten biodiversity?

Habitat loss, pollution, climate change, invasive species, and overexploitation.

What is a keystone species? Give an example.

A species that has a major role in maintaining ecosystem structure. Example: Sea otters controlling sea urchin populations.

What are eukaryotic microbes and their main groups?

Microorganisms with membrane-bound organelles; includes fungi, protists, and some algae.

Describe the structure and role of fungi.

Fungi have chitin in their cell walls and ergosterol in membranes. They decompose matter, form symbioses, or cause disease.

Differentiate between yeast and mold.

Yeasts are unicellular and reproduce by budding; molds are multicellular with filamentous growth.

What are dimorphic fungi?

Fungi that can switch between yeast and mold forms depending on environmental conditions

List examples of superficial, subcutaneous, and systemic mycoses.

Superficial: Tinea; Subcutaneous: Sporotrichosis; Systemic: Cryptococcosis.

What is the endosymbiotic theory?

Eukaryotic organelles like mitochondria and chloroplasts originated from engulfed prokaryotes

Name four parasitic protists and diseases they cause.

Giardia (giardiasis), Entamoeba (amebiasis), Plasmodium (malaria), Trypanosoma (Chagas disease)

How is malaria transmitted and what is its life cycle?

Transmitted by Anopheles mosquitoes; sporozoites infect liver, develop into merozoites, which infect red blood cells.

What are the transmission routes of protist pathogens?

Fecal-oral, insect vectors, sexual contact, congenital, organ transplant

What is natural selection and who proposed it?

A process where organisms with favorable traits survive and reproduce more; proposed by Charles Darwin.

State Darwin's four postulates of natural selection

Variation exists, traits are heritable, more offspring are produced than can survive, survival is not random.

What is 'fitness' in evolutionary terms?

An organism's ability to survive, reproduce, and pass on its genes to the next generation.

List the sources of genetic variation.

Mutation, gene duplication, chromosomal rearrangements, and sexual recombination.

Explain allopatric and sympatric speciation.

Allopatric: geographic isolation; Sympatric: reproductive isolation without geographic separation.

What are prezygotic and postzygotic barriers?

Prezygotic: prevent mating/fertilization; Postzygotic: prevent viable or fertile offspring

Define the biological species concept

Species are groups of interbreeding natural populations reproductively isolated from others.

How do phylogenetic trees help us understand evolution?

They show relationships based on shared ancestry and trait inheritance.

What is a monophyletic group?

A clade containing a common ancestor and all its descendants.

What is the difference between homologous and analogous traits?

Homologous traits come from a common ancestor; analogous traits evolved independently