Zoology: Characteristics of Life

Flashcards covering the five core characteristics of life, energy acquisition, homeostasis, reproduction, and evolution, with examples (peacock flounder and orchid-wasp) from the lecture notes.

What is the first core characteristic of life?

Life is organized, showing a hierarchical pattern of structures from atoms to molecules to organelles to cells to tissues to organs to multicellular organisms.

What are the building blocks that bond to form molecules, organelles, cells, tissues, and organisms?

Atoms bond to form molecules, which form organelles, cells, tissues, organs, and ultimately multicellular organisms.

What is the second core characteristic of life?

Life requires energy to power chemical reactions and processes that maintain organization and support growth, development, and reproduction.

What are the two major energy-based groups of organisms?

Producers (autotrophs) and consumers (heterotrophs).

Who are producers (autotrophs) and what do they do?

Producers like plants, algae, and photosynthetic bacteria extract energy from the nonliving environment and form organic molecules (sugars) via photosynthesis.

Who are consumers (heterotrophs) and how do they obtain energy?

Consumers, including fungi and animals, cannot make their own food and obtain energy by eating producers or other consumers.

What is the third core characteristic of life?

Life maintains an internal constancy, known as homeostasis.

What cellular-level aspects does homeostasis involve?

Balance of water, steady pH, appropriate salinity, and maintaining a narrow temperature range; about 70 trillion cells maintain balance, requiring energy.

What is the fourth core characteristic of life?

Life grows, develops, and reproduces.

What are the two modes of reproduction?

Asexual reproduction and sexual reproduction.

Describe asexual reproduction.

New individuals are produced from a single parent; offspring are clones; some bacteria exchange DNA fragments to alter traits; some multicellular organisms (e.g., sponges) reproduce asexually in emergencies.

Describe sexual reproduction.

Two individuals unite their genetic material to produce offspring that are genetically unique with new trait combinations.

What is the fifth core characteristic of life?

Evolution — change in populations over time driven by natural selection.

What is natural selection?

Enhanced reproductive success of individuals based on inherited traits that make them better adapted to their environment.

How does the peacock flounder illustrate adaptation?

It has eyes on one side and a flattened body, enabling camouflage and effective predation in its bottom-dwelling, aquatic habitat.

How does the orchid-wasp interaction illustrate adaptation?

The orchid emits a scent resembling a female wasp to attract males; pollen sticks to the wasps and is transferred to other orchids, promoting pollination.

What does the orchid-wasp interaction demonstrate about evolution?

Coordinated adaptations that enable pollination and inheritance of traits via natural selection.

Approximately how many cells are in the human body?

About 70,000,000,000,000 (70 trillion) cells.

Why is energy needed to maintain organization and internal constancy?

Because maintaining cellular order and homeostasis requires energy to drive chemical reactions and homeostatic processes.