Unit A: Biological Diversity (Social and Environmental Contexts) Careers in Biology
Overview: Biological diversity is reflected in the range of species found in local and global environments, and by subtle variations in characteristics found within individual species. In this unit students learn that diversity is maintained through natural processes of sexual and asexual reproduction, though the survival of individual species-and variations within those species may be influenced by ecological and human-caused factors. Students examine trends toward loss of diversity, and examine related issues concerning environmental quality and the impact of technologies.
This unit builds on ideas introduced in Grade 7, Unit A: Interactions and Ecosystems, and introduces ideas that will be developed finther in Science 20, Unit B: Changes in Living Systems. Focussing Questions: What is biological diversity?
By what processes do diverse living things pass their characteristics on to future generations?
Students will: Investigate and interpret diversity between species and within species, and describe how diversity contributes to species survival.
observe variation in living things, and describe examples of variation between species and within species (e.g., observe and describe characteristics that distinguish two closely related species)
investigate adaptations of species to their environments, and infer the function of different structures (e.g., interpret variation in animal structures for locomotion or for securing food)
identify examples of niches, and describe the role of variation in enabling closely related living things to survive in the same ecosystem (e.g., investigate different bird species found in a local park ecosystem, and infer how each is adapted to life within that ecosystem)
investigate and interpret dependencies between species that link the survival of one species to the survival of others (e.g., by providing habitat, food, means of fertilization, or a source of oxygen)
Students will: Investigate the nature of reproductive processes and their role in transmitting species characteristics.
distinguish between sexual and asexual reproduction, and identify and interpret examples of asexual and sexual reproduction in different species describe representative types of asexual reproduction (e.g., fission in the amoeba, budding in hydra, production of zoospores in some fungi) describe representative types of sexual reproduction (e.g., conjugation in bacteria, cross-fertilization in seedplants, sexual reproduction in mammals) describe examples of organisms that show both sexual and asexual reproduction (e.g., yeasts that reproduce both by budding and sexual reproduction; plants that reproduce through suckering, runners or bulbs, as well as by seedproduction) describe the formation of zygote and embryo in plant and animal reproduction (movies) describe examples of variation in characteristics within a species and identify examples of both discrete and continuous variation (e.g, hand clasping preference is an example of a discrete variation; the length of human hands varies on a continuum)
identify examples of dominant and recessive characteristics (e.g., dominance of brown eyes over blue eyes) and recognize that dominance and recessiveness provide only a partial explanation for the variation of characteristics in offspring
Students will: Describe, in general terms, the role of genetic materials in the continuity and variation of species characteristics, and investigate and interpret related technologies.
distinguish between cell division by binary fission, and cell division in the formation of sex cells (zygote); and describe-in general terms-the syntheses of genetic materials that takes place during fertilization.(glossary) (Note: At this level, students should understand that formation of sex cells involves the halving of the cell's genetic materials, and that this process leads to zygote formation. Opportunity for further study of the specific mechanisms of cell division (mitosis and meiosis) will be provided in later courses) compare sexual and asexual reproduction, in terms of the advantages and disadvantages (e.g., recognize that asexual reproduction provides an efficient means of transmitting characteristics, and that sexual reproduction provides an opportunity for recombination of characteristics)
distinguish between and identify examples of artificial and natural selection (e.g.; evolution of beak shapes in birds; development of high milkproduction in dairy cows)
describe, in simple terms, some of the newly emerging technologies for recombining genetic material and identify questions and issues related to their application
Students will:
Identify impacts of human action on species survival and variation within species, and analyze related issues for personal and public decision making. describe the relative abundance of species on Earth and in different environments (e.g., note the overall abundance of insect species; note that in harsh environments there are relatively fewer species found than in temperate and tropical environments)
describe ongoing changes in biological diversity through extinction and extirpation of native species, and investigate the role of environmental factors in causing these changes (e.g., investigate the effect of changing river characteristics on the variety of species living in the river, investigate the effect of changing land use on the survival of wolf or grizzly bearpopulations)
evaluate the success and limitations of various local and global strategies for minimizing loss of species diversity (e.g., breeding of endangered populations in zoos, development of seed banks; designating protected areas, development of internationaltreaties regulating trade of protected species and animal parts)