13.4 Food Chains And Food Webs

Updates: Unit guide 13.4 # 1 – 4 due Homework: –Read 4.4, 4.5 –HW: Unit guide 4.4/4.5 # 1 – 5 due Tuesday –Modeling Predation lab due Wednesday Unit 4 quiz 2 Wednesday

13.4 Food Chains And Food Webs Which pigment absorbs sunlight to begin the transformation? A) Chlorophyll B) chloroplasts C) water D) oxygen Which chemical is used for an electron supply? A) water B) sugars C) oxygen D) carbon dioxide Which process requires ATP? A) light absorption B) Calvin cycle C) both D) none Which process actually produces sugars? A) light dependent B) light independent

13.4 Food Chains And Food Webs Northern Two-lined Salamander Size: inches ( cm) in length Status: Abundant Habitat: Stream side along small to medium sized streams, springs, and hillside seeps with sandy to gravel substrate and rock or log cover.

13.4 Food Chains And Food Webs LEQ: How do food webs model feeding relationships? Activator: –Leaf senescence –Identify what the reactants (including light) and products of photosynthesis are used for: Key terms – food chain, trophic level, specialist, generalist, food web, keystone species

13.4 Food Chains And Food Webs Matter and energy transformations continue when producers are consumed A food chain shows a sequence of feeding relationship(s) between a producer and a consumer(s) –Producers consumed via herbivory –Herbivores are consumed via predation DESERT COTTONTAILGRAMA GRASSHARRIS’S HAWK

13.4 Food Chains And Food Webs Trophic levels describe how energy and matter are distributed. –Primary producers transform sunlight into carbohydrates –Primary consumers eat producers. –Secondary consumers eat herbivores. –Tertiary consumers eat secondary consumers. Organisms in food chains are assigned trophic levels.

13.4 Food Chains And Food Webs Food webs reveal community structure through species interactions and matter/energy flow

13.4 Food Chains And Food Webs Specialist feeders (left) primarily eat one specific organism (rare) Generalist feeders (right) have a varying diet. –May be widely distributed Competition drives the evolution of feeding behaviors.

13.4 Food Chains And Food Webs Food webs can show feeding relationships, energy flow (flux) and/or affects on population growth

13.4 Food Chains And Food Webs Species abundance is related to food web interactions A dominant species is more numerous than its competitors: –Most abundant trophic level member –Large populations –Direct effects

13.4 Food Chains And Food Webs A keystone species have an unusually large effect on its ecosystem that greatly exceeds its abundance. –Ecosystems change when absent keystone

13.4 Food Chains And Food Webs Some species “engineer” the structure of an ecosystem Are beavers a keystone species and what is their role in an aquatic ecosystem?

13.4 Food Chains And Food Webs Beavers: Keystone Species? Why do you think it might be advantageous for beavers to provide shelter and food to other species such as muskrats, frogs, moose, etc.? In the video, the narrator says, “beavers turn desserts into gardens.” Use examples from the video to support this statement. Discuss whether or not you think that beavers are a keystone species, using examples from the video to support your view.

13.4 Food Chains And Food Webs Focus: Pisaster regulates food web structure Keystones may be generalist predators that suppress the population growth of an otherwise competitive species –Predict what will happen if Pisaster is removed

13.4 Food Chains And Food Webs Modeling Predation

13.4 Food Chains And Food Webs Shows a single sequence of feeding relationships: A) food chain B) food web C) trophic structure D) keystone Which of the following organisms eats only one type of organism? A) specialist B) generalist C) keystone sp. D) dominant sp. Which of the following species has an usually large effect on an ecosystem? A) keystone sp. B) dominant sp. C) generalist D) specialist

13.4 Food Chains And Food Webs

How Plants Defend Themselves What is wild tobacco’s "secret chemical weapon?” What is wild tobacco’s defense against predators like the hornworm caterpillar, which is immune to nicotine? How does the wild tobacco plant distinguish one type of predator from another and defend itself accordingly?