Year 11 Biology – Semester 1 Exam Revision Answers

Independent Variable

The variable that is deliberately changed by the experimenter to test its effect.

Dependent Variable

The variable that is measured or observed in response to changes in the independent variable.

Controlled Variables

Variables that are kept constant to ensure that the experiment is fair and that the results are valid.

Transects

A straight line across a habitat along which observations and measurements are made of organisms at regular intervals.

Quadrats

Square frames of a known size used to sample and count the number of organisms within a given area.

Population Density

Calculated by dividing the number of individuals of a species by the area sampled.

Population Size

Estimated by multiplying the average number of individuals per quadrat by the total number of quadrats.

Biodiversity

The variety of life in all its forms, including genetic diversity, species diversity, and ecosystem diversity.

Genetic Diversity

Variation in the genes of individuals within a species.

Species Diversity

The number and variety of species in a particular region.

Ecosystem Diversity

The variety of ecosystems in a given place.

Natural Selection

The process by which individuals with favourable traits are more likely to survive and reproduce.

Stabilising Selection

Selection that favours the average phenotype and selects against extremes.

Disruptive Selection

Selection that favours individuals at both extremes of the trait range.

Directional Selection

Selection that favours one extreme phenotype, causing a shift in the population trait over time.

Levels of Classification

Hierarchy in biology: Kingdom, Phylum, Class, Order, Family, Genus, Species.

Morphological Species Concept

Defines species based on shared physical characteristics.

Biological Species Concept

Defines species as groups of organisms that can interbreed and produce fertile offspring.

Phylogenetic Species Concept

Defines species based on shared evolutionary history and genetic evidence.

Fish

Aquatic vertebrates with gills and fins.

Amphibia

Vertebrates that start life in water and develop lungs for life on land.

Reptilia

Vertebrates with scaly skin that lay leathery eggs on land.

Aves (Birds)

Warm-blooded vertebrates with feathers, beaks, and hard-shelled eggs.

Mammals

Warm-blooded vertebrates with hair or fur that produce milk for their young.

Mosses

Non-vascular plants that reproduce using spores.

Ferns

Vascular plants that reproduce via spores.

Conifers

Vascular plants that reproduce using seeds in cones.

Flowering Plants

Vascular plants that reproduce using seeds in flowers.

Monocots

Plants with one seed leaf and flower parts in multiples of three.

Dicots

Plants with two seed leaves and flower parts in multiples of four or five.

Competition

Involves intra-specific and inter-specific competition between individuals for resources.

Mutualism

A symbiotic relationship where both species benefit.

Commensalism

A symbiotic relationship where one species benefits while the other is unaffected.

Parasitism

A symbiotic relationship where one species benefits at the expense of the other.

Predator-Prey Relationship

The cyclical relationship between predator and prey populations.