exam 1 study guide

Precambrian and Early Life

  • Unicellular life forms dominated in the Precambrian era.

  • Notable organisms: Chordoflagellates.

Cambrian Period

  • Cambrian Explosion:

    • Major increase in biological diversity caused by meteor impact.

    • Resulted in higher levels of available oxygen, more continental shelf area, and the presence of Hox genes leading to increased body plan diversity.

Ordovician Period

  • Early Ordovician:

    • First fish appeared; development of armor plating.

  • Late Ordovician:

    • Evolution of bony jaws allowed for predation.

    • Early colonization of land by plants.

Devonian Period

  • Notable for lobe-finned fish; early vertebrates began to occupy land.

    • Key adaptation for colonization of land.

Permian Period

  • Marked by the largest known extinction event, primarily due to volcanic activity.

Triassic and Jurassic Periods

  • Triassic:

    • Notable for diversification of species post-extinction.

  • Jurassic:

    • Increased body size in multiple species and further extinction events.

Cretaceous Period

  • Closest ancestors of modern fish appeared.

  • Extinction event at the Cretaceous-Paleogene boundary.

Animal Physiology

Respiratory and Circulatory Systems

  • Diaphragm's role in respiration:

    • Contracts and relaxes to manage air flow.

    • Allows for different mechanisms in various species (suction mechanism, tidal ventilation).

  • Importance of heat management in animals:

    • Thermoregulation involves blood vessel constriction and dilation in response to temperature changes.

Homeostasis

  • Mechanisms to maintain internal stability in dynamic environments:

    • Homeotherms maintain a stable internal temperature (e.g., birds, mammals).

    • Poikilotherms have body temperature that fluctuates with the environment (e.g., reptiles).

Tissue Types in Animals

Nervous Tissue

  • Composed of neurons; serves as the communication system of the body.

Muscle Tissue

  • Skeletal: volitional muscles attached to bones.

  • Cardiac: involuntary muscles found in the heart.

  • Smooth: muscles in the digestive tract and blood vessels.

Epithelial Tissue

  • Forms surfaces of organs and the skin, serving protective and absorptive functions.

Connective Tissue

  • Comprises the extracellular matrix; includes varied types such as adipose tissue (brown fat and white fat).

Metabolism and Body Size

  • Metabolic rates are higher in smaller animals due to their increased surface area-to-volume ratio.

  • Smaller animals lose heat faster than larger ones.

Evolution of Animal Life

Animal Origins

  • Debate surrounding the origin of multicellular animals:

    • Sponges considered the closest living relatives to the common ancestor of all animals.

  • Cambrian Explosion led to significant diversification in marine organisms.

Evolution of Fish

  • Early evolution of fish in the Ordovician: development of armor and jaws.

  • Evolution continued into the Devonian with the diversification of bony fish;

    • Placoderms and lobe-finned fish emerged.

Land Adaptation Challenges

  • Major challenges for land colonization: gravity, moisture loss, and breathing.

  • Development of physiological adaptations to manage these challenges (e.g., lungs in tetrapods).

Extinction Events in Animal Evolution

Cambrian: caused by meteor impact

  1. Late Ordovician: Result of volcanic activity and anoxia.

  2. Late Devonian: Global cooling and ocean anoxia.

  3. Permian-Triassic: Significant global warming and ocean acidification. volcano. Largest one

  4. Triassic-Jurassic: Volcanic eruptions contributing to global warming.

Homeostasis in Animals

  • Homeostasis defined as stability in the internal environment despite external changes.

  • Q10 Temperature Coefficient measures the sensitivity of reactions to temperature change.

  • Feedback mechanisms play crucial roles in maintaining homeostasis.

  • Hibernation and metabolic adaptations in response to environmental changes.