General Biology Final Exam Study Guide: Genetics, Evolution, and Human Body Maps

Genetics

X-Linked Traits

X-linked traits are genetic characteristics determined by genes located on the X chromosome. These traits often display unique inheritance patterns due to the difference in sex chromosomes between males (XY) and females (XX).

• Definition: Traits controlled by genes on the X chromosome.

• Inheritance: Males are more likely to express recessive X-linked traits because they have only one X chromosome.

• Example: Color blindness and hemophilia are common X-linked disorders.

Autosomal Traits

Autosomal traits are determined by genes located on the autosomes (non-sex chromosomes).

• Definition: Traits inherited via the 22 pairs of autosomes.

• Inheritance: Both males and females have equal probability of inheriting autosomal traits.

• Example: Cystic fibrosis and sickle cell anemia are autosomal recessive disorders.

Properties of Pathogens

Pathogens are organisms that cause disease in their hosts. They include bacteria, viruses, fungi, and parasites.

• Key Properties: Infectivity, virulence, transmission mode, and ability to evade host defenses.

• Example: Streptococcus pneumoniae (bacteria), Influenza virus (virus).

Codominance

Codominance occurs when both alleles in a heterozygote are fully expressed, resulting in offspring with a phenotype that shows both traits equally.

• Definition: Both alleles contribute to the phenotype.

• Example: AB blood type in humans, where both A and B antigens are expressed.

Incomplete Dominance

Incomplete dominance is a genetic scenario where the heterozygote displays a phenotype intermediate between the two homozygotes.

• Definition: Neither allele is completely dominant; the phenotype is a blend.

• Example: Snapdragon flower color: red (RR), white (rr), pink (Rr).

Evolution

Adaptation

Adaptation refers to the process by which organisms become better suited to their environment through evolutionary changes.

• Definition: A trait that increases an organism's fitness in its environment.

• Example: Camouflage in chameleons.

Bottleneck Effect

The bottleneck effect is a sharp reduction in the size of a population due to environmental events, leading to reduced genetic diversity.

• Definition: Loss of genetic variation after a drastic population decrease.

• Example: Northern elephant seals experienced a bottleneck due to hunting.

Founder Effect

The founder effect occurs when a new population is established by a small number of individuals, resulting in limited genetic variation.

• Definition: Genetic drift resulting from a small founding population.

• Example: Amish populations with higher frequency of certain genetic disorders.

Genetic Drift

Genetic drift is the random change in allele frequencies in a population, especially significant in small populations.

• Definition: Random fluctuations in allele frequencies over time.

• Example: Loss of alleles in isolated island populations.

Genetic Variation

Genetic variation is the diversity of gene frequencies within a population, essential for evolution and adaptation.

• Sources: Mutation, recombination, gene flow.

• Importance: Enables populations to adapt to changing environments.

Adaptations

Adaptations are inherited characteristics that enhance an organism's ability to survive and reproduce.

• Types: Structural, physiological, behavioral.

• Example: Thick fur in arctic animals.

Fitness

Fitness is a measure of an organism's ability to survive and reproduce in its environment.

• Definition: Relative reproductive success of an individual.

• Equation: $w = \frac{N_{offspring}}{N_{average}}$

Descent with Modification

Descent with modification describes how species change over generations, with new traits arising and being passed on.

• Definition: Passing traits from parent to offspring, with changes over time.

• Example: Evolution of Darwin's finches on the Galápagos Islands.

Natural Selection

Natural selection is the process by which organisms with advantageous traits survive and reproduce more successfully.

• Definition: Differential survival and reproduction due to trait variation.

• Types: Directional, stabilizing, disruptive selection.

• Equation: $\Delta p = \frac{spq}{1 - sq}$ (change in allele frequency)

Charles Darwin

Charles Darwin was a naturalist who developed the theory of evolution by natural selection.

• Key Work: "On the Origin of Species" (1859).

• Contribution: Proposed that species evolve over time through natural selection.

Hardy-Weinberg Principle & How to Calculate

The Hardy-Weinberg principle describes a population that is not evolving, where allele and genotype frequencies remain constant.

• Equation: $p^2 + 2pq + q^2 = 1$

• Assumptions: No mutation, migration, selection, random mating, large population size.

• Application: Used to estimate allele frequencies in populations.

Types of Selection (Disruptive, Directional, Stabilizing)

Selection can act on traits in different ways, shaping population variation.

• Directional Selection: Favors one extreme phenotype.

• Stabilizing Selection: Favors intermediate phenotypes.

• Disruptive Selection: Favors both extremes over intermediates.

Evidence of Evolution (Homologous Structures, DNA, Embryology)

Multiple lines of evidence support the theory of evolution.

• Homologous Structures: Anatomical features with similar origin but different functions (e.g., human arm and whale flipper).

• DNA: Genetic similarities among species indicate common ancestry.

• Embryology: Similar embryonic development patterns among related species.

Map of Human Body

Body Planes

Body planes are imaginary lines used to divide the body into sections for anatomical study.

• Sagittal Plane: Divides body into left and right parts.

• Coronal (Frontal) Plane: Divides body into anterior (front) and posterior (back) parts.

• Transverse Plane: Divides body into superior (upper) and inferior (lower) parts.

Body Cavities

Body cavities are spaces within the body that house organs.

• Dorsal Cavity: Contains the brain and spinal cord.

• Ventral Cavity: Includes thoracic (heart, lungs) and abdominopelvic (digestive, reproductive organs) cavities.

Body Plane	Description
Sagittal	Divides body into left and right
Coronal (Frontal)	Divides body into front and back
Transverse	Divides body into upper and lower

Body Cavity	Main Organs
Dorsal	Brain, spinal cord
Ventral	Heart, lungs, digestive organs, reproductive organs