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Text (7th ed.): Ch. 1, pp. 2-6; Ch. 5, Ch. 15

Dr. W. Crone (303 FTZ, 629-7439, cronewil@hvcc.edu, http://www.hvcc.edu/academ/crone/index.html)


possible web site: http://www.ucmp.berkeley.edu/exhibit/exhibits.html (useful!)

possible HVCC a/v:"Life on Earth" videos by David Attenborough: we'll see some this fall

1. Science: a way of thinking. Observations are important, theories changed as more observations made and new hypotheses tested.

2. Life: main defining feature is its complex organization and four general areas of genetics, cell theory, evolution, and ecology.2 These four general themes help to unify the bewildering diversity of life, and explain life at different levels, which are, from smallest to largest:

1) atom: the fundamental unit of matter, e.g., atoms of carbon

2) molecule: atoms joined together, e.g., DNA

3) cell: the fundamental unit of life, e.g., ameba, neuron

4) tissue: group of similar cells with a common function, e.g., muscle tissue

5) organ: unit made up of more than one tissue type, e.g., stomach, kidney

6) system: association of organs for a common purpose, e.g., nervous

7) individual: organism

8) population: group of organisms

9) ecosystem: interactions of populations among themselves and their surroundings

3. Taxonomy, or science of classification, based on the two main concepts of Linnaeus: binomial species name and hierarchical groupings. Classification is our attempt to show the relatedness of organisms, and hence, should reflect evolutionary relationships."King Philip, Come Out For Goodness Sake:" Kingdom, phylum, class, order, family, genus, species. The modern classification update of cladistics emphasizes common descent.

Animal kingdom: multicellular organisms without cell walls that ingest nutrients.

phylum: a distinct body plan.

class: a major variation in the body plan, usually regarding a particular lifestyle

species: in some ways, the most"real" of these hierarchies--often thought of in terms of interbreeding or interbreedable populations.

4. Life activities of animals. Animals will utilize different strategies for these life activities. For example, feeding and locomotion or movement: search for food and/or escape from predators. Sedentary animals, e.g., clam or spider, will stay in one place but can move about, while sessile animals, e.g., sponge, remain attached to one spot but often propel food their way. Reproduction: production of offspring. Sexual vs. aseuxal (whether or not recombination of genes are involved).

5. Unusual aspects of different animals. Compare/contrast active animals like ourselves to sessile, colonial animals like coral polyps. Consider different symmetries, presence or absence of body cavity (coelom), types of digestion, circulation, etc.

symmetry: arrangement of parts around a point or axis.

bilateral symmetry: arrangement of body parts so that a single midline plane divides the body into mirror images

radial symmetry: arrangement of body parts so that any plane through a central axis divides the animal into mirror images

  1. Orientation of animals. anterior/posterior (front [head]/back [tail]), distal/proximal (away/towards site of attachment), dorsal/ventral (back/belly), inferior/superior (below/above), median/lateral (middle/side) and transverse (cross) vs. median or midsagittal planes vs. frontal or coronal planes of section.


7. Ecology is the study of the relationships of organisms to their environment and to other organisms. A major part of ecology is the energy flow through the ecosystem, or collection of populations and habitats.1 Photosythetic plants capture light energy and store it in the form of carbohydrates, fats, and proteins. We can call plants producers as a result. A primary consumer is a plant-eating animal, and a secondary consumer eats these primary consumers. This food chain is a flow of energy in the form of nutrients from one to another. There will be more primary producers and consumers than secondary consumers, since less energy is available as one progresses through the food chain.

8. Populations are groups of individuals of the same species that occupy a given area at the same time. Animal populations change over time as the results of births, deaths, and dispersals. A related point about populations is K- and r-selection. The population size that a particular environment can support is the carrying capacity. Populations that tend to run near the carrying capacity of a community are made of long-living individuals that have low reproductive rates and (often) care for their offspring, as with humans (K-selection). In contrast, populations that are r-selected produce many young quickly, with few survivors, as in most of the invertebrates.1

9. Populations will show one of two growth patterns: exponential and logistic growth. In exponential growth, the population increases multiplicatively, e.g., 2-4-8-16-32-64- and so on in 2n fashion. But eventually, there is a limiting resource, like food, water, or space, and the population grows in a sigmoid or s-shaped curve, as in logistic growth. With these different growth rates, the age distribution of an exponentially-growing population is different than that of a logistically-growing population, with proportionately more young than old in exponentially-growing populations.1

10. Niche: the role of an organism within the structure and function of an ecosystem. Thinking about a niche includes thinking about the surroundings of the organism, its habitat. Not only does an organism have a role it could play (the fundamental niche), but it also has a role that it does play in a particular setting (the realized niche). The types of interspecific interactions (i.e., those between and among species) highlight how a fundamental niche can be narrowed down into the realized niche. Examples include:

  1. Parasitism: a form of symbiosis when one organism lives in or on another (the host). We will see many examples, especially with roundworms and flatworms.
  2. Commensalism: Another symbiotic relationship, this time with one member benefiting, and the other neither being harmed or helped, e.g., Entamoeba gingivalis, an ameba, in our mouths
  3. Mutualism. A symbiotic relationship where both benefit. Clown fish and sea anemone; lichen with alga and fungus.

11. On a grander scale, interactions with the physical environment also play a major role.

Biogeochemical cycle: natural processes that recycle nutrients in various chemical forms from the nonliving, physical environment, to living organisms, and then back to the nonliving environment, e.g., C, N, P, H2O cycles.1

Biome: a large, terrestial ecosystem characterized by particular forms of vegetation. The locations of these biomes are determined by climate, especially temperature and precipitation. Different biomes include tundra, taiga, temperate forest, rain forest, grassland, savanna, chaparral, and desert.1

12. All of these factors and more lead to species variety within communities or biodiversity. A species represents a gene pool, a source of genetic information that has been shaped by millions of years of evolution, and which is lost by extinction.

1 CP Hickman et al., Biology of Animals, 7th ed. (WCB McGraw-Hill, Boston, 1998), pp. 113, 115-6, 118-9, 123-6, 128

2 SA Miller, JP Harley, Zoology, 2nd ed. (WC Brown, Dubuque, IA, 1994), Ch. 1


|main page| |background| |03028: Physiology| |03048: Anatomy|

|03050: Invertebrate Zoology| |03051: Vertebrate Zoology| |03074: Economic Botany|


Please send comments and questions to: cronewil@hvcc.edu


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This page updated on September 15, 1999