Unit D – Changes in Living Systems

1. Unit D – Changes in Living Systems (Pages 402 - 515)

2. In this unit you will: • Learn about the biotic and abiotic components of a living system and how they interact • Conduct a field study • Learn about the mechanisms of populations change

3. Chapter 1 – The Biosphere of Life

4. Biotic factors include all living organisms in the environment Examples: plants, insects, animals • Abiotic factors include all physical, non-living parts of the environment Examples: water, pH of water and soil, nutrients in soil, temperature, light intensity Abiotic and Biotic Factors An ecosystem is all the organisms (biotic) in an area, as well as the non-living (abiotic) factors with which they interact.

5. Habitat A habitat is all the biotic and abiotic factors present in an area that encourage the reproduction and survival of a particular organism

6. Algal blooms can result in the depletion of oxygen dissolved in water. What factors can result in an algal bloom? Excess amount of nitrogen and phosphorus act as a fertilizer for algae. This causes the algae to grow out of control. A thick mat of algae develops on the surface of the water. How does an algal bloom affect the abiotic and biotic factors of a body of water? Layer of algae block out sunlight and prevents gas exchange on the surface of the water. Plants below the surface die and decompose. Oxygen levels drop and other animals in the lake will die. Causes a decrease in biodiversity.

7. Ecology is the study of the interactions of living organisms with one another and with their physicalenvironment • A population is a group of organisms, all of the same species, living in the same place at the same time • A community is the interacting populations living in a certain area at a certain time

8. Symbiosis is a long-lasting ecological relationship that benefits at least one organism of two different species that live in close contact • Symbiotic relationships can be described as: • Mutualism: both benefit (+/+) • Commensalism: one benefits, other is not affected (+/0) • Parasitism: one organism, called the parasite, benefits at the expense of the other, called the host (+/-)

9. . Watch the clips of animal relationships and determine what form of symbiosis they exhibit. Goby and Pistol Shrimp Mutualism – both benefit Snapper and Tongue Biter Parasitism – tongue biter benefits, snapper does not. When parasite dies, so does the snapper Hermit Crab and Sea Anemone Mutualism – both benefit

10. Predation is an interaction where one organism (predator) kills and eats another organism (prey) • What are the similarities between predation and parasitism? What are the differences? Similarities: - one organism benefits, the other is harmed (killed) Differences: - predation is short-lived interaction. - parasitism is a long-lived interaction. - parasitism does not aim to kill the host

11. Competition is an interaction in which two or more organisms compete for the same limited resource • May occur within the same species or amongst species • Examples of limited resources: • Food, water, nutrients, habitat, mate, light

12. 1.3 – The Web of Life Organisms fulfill different roles in transferring energy within an ecosystem Roles: Producer Consumer Decomposer

13. Producers Use the process of photosynthesis to convert energy from the Sun into sugars and other organic compounds Produce organic compounds from inorganic nutrients found in soil, air and water

14. Consumers • A consumer is an organism that uses other organisms as a source of energy Consumers can be classified as: • Primary consumer (or herbivore) – eats green plants, algae, or phytoplankton • Secondary consumer (omnivore or carnivore)– eats herbivores • Tertiary consumer (omnivore or carnivore)– eats secondary consumers • Scavenger – animal that feeds on dead animals that it did not kill itself

15. grass obtains energy from eating producers grasshopper secondary consumer obtains energy from eating primary consumers tertiary consumer hawk omnivore sparrow Obtains energy from animals it does not kill itself Coyote magpie primary, secondary, tertiary consumer Breaks complex molecules into simpler molecules (recycles) Bacteria fungi

16. Energy Flow in an Ecosystem • The Sun is the primary source of energy is almost every ecosystem on Earth • Each step in the energy pathway through an ecosystem is called a trophic level • Only 10% of energy from each trophic level is available to the next trophic level (rule of 10) • This is illustrated by an energy pyramid

18. Pyramid of Biomass Energy stored at each trophic level is difficult to measure Biologists approximate the energy stored at each level by using a pyramid of biomass Biomass is a measure of all the dry mass of all organisms for each trophic level Why is it important that this is a “dry” measure? water content of the organisms does not contain energy

19. Pyramid of Numbers A pyramid of numbers is another way to describe trophic levels How many producers are required to support the 2 tertiary consumers in the grassland ecosystem?

20. Food Chains • A food chain shows the pathway along which food is transferred from one trophic level to the next • Food chains: • Always begin with the producers • Show how energy is passed along as one organism feeds on another • Shows detail of feeding between trophic levels • Can be terrestrial or aquatic

21. Food Webs • A food web shows the interconnecting feeding relationships within an ecosystem • shows the many food chains the make-up an entire ecosystem • This is called a food web because the various food chains overlap and interconnect. • Use the food web to identify: • Producers algae • Primary consumers Tadpole, mosquito, snail • Secondary consumers Stickleback, frog, N. Pike • Tertiary consumers N. Pike, grebe, frog (organisms can occupy more than one trophic level, depending on what they are eating)