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Food Connections

Food Connections. SNC 1D R.H. King Academy. What is the origin of all animals’ food?. PLANTS! Whether herbivore or carnivore, all of our food comes from plants. Photosynthesis.

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Food Connections

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  1. Food Connections SNC 1D R.H. King Academy

  2. What is the origin of all animals’ food? PLANTS! Whether herbivore or carnivore, all of our food comes from plants.

  3. Photosynthesis • Plant leaves contain chlorophyll in the chloroplast organelle. Plants use chlorophyll to capture the energy in sunlight and convert it into chemical energy. They then use this chemical energy for all the processes in their cells. • This process is called photosynthesis. The equation for photosynthesis is: Carbon dioxide gas + water + sunlight  glucose + oxygen gas

  4. Photosynthesis

  5. Photosynthesis • Glucose is a simple form of sugar. All sugars are carbohydrates, and carbohydrates contain energy. Therefore, carbohydrates are stored energy. • Oxygen gas is what we breathe in. The air we breathe is 21% oxygen, and almost all of it was produced by photosynthesis. This includes plants on land and in the ocean.

  6. Cellular Respiration • Cellular Respiration is the process of using energy to keep our bodies functioning. • Both plants and animals need a continuous supply of energy for growth, repair of tissues, and reproduction. • The process plants and animals use to obtain energy from glucose is called cellular respiration. In cellular respiration, glucose combines chemically with oxygen from the air, in what looks like almost the reverse of photosynthesis. The equation is: Glucose + oxygen gas  Carbon dioxide gas + water + energy

  7. Photosynthesis vs. Cellular Respiration • Do plants perform photosynthesis? • Do animals perform photosynthesis? • Do plants perform cellular respiration? • Do animals performs cellular respiration? • Therefore, plants can make their own food (photosynthesis) and use it (cellular respiration). Animals cannot make their own food, but they do use food. How do animals get their food?

  8. Photosynthesis and Cellular Respiration • What is the relationship between photosynthesis and cellular respiration?

  9. Trophic Levels • In a food chain, food moves through trophic levels • Producers are plants. They are ALWAYS at the first trophic level, located at the bottom.

  10. Trophic Levels • Producers are plants. They make their own food through photosynthesis • Primary consumers are herbivores. They eat plants. Give an example. • Secondary consumers are carnivores. They eat primary consumers. Give an example. • Tertiary consumers are carnivores. They eat secondary consumers. Give an example. • A carnivore that has no predators is called a “top carnivore”. Give an example.

  11. Omnivores • Omnivores eat both plants and animals. For example, a bear. So what is its trophic level? Well let’s look at what it eats: • When the bear is eats berries, it is a primary consumer. • When the bear is eats rabbits, it is a secondary consumer. • When the bear is eats salmon, it is a tertiary consumer • However, if you have to choose one trophic level for the sake of simplicity, you must state the bear’s highest trophic level: “tertiary consumer”. • A bear is also a “top carnivore” because it has no predators (unless you consider humans!)

  12. Detritivores and Scavengers • Detritivores eat organic matter (dead organisms and their waste). • Scavengers are a type of carnivore that does not hunt animals. Instead, it eats the leftovers of dead or dying animals. • Which of the species below is a detritivore? Which is a scanveger?

  13. Decomposers • Decomposers play an essential role in food chains. • Decomposers break down organic matter. They take nutrients from the organic matter and release them back into the ecosystem. • Fungi and many bacteriaare decomposers. Instead of consuming food, they release chemicals called enzymes into the organic matter. These enzymes break down the organic matter and release nutrients. The decomposers can then absorb the nutrients. • Detritivores are classified as decomposers, but not all decomposers are classified as detritrvores since many fungi and bacteria cannot directly eat organic matter.

  14. Decomposers • This fungus is feeding on the organic matter in the soil. As it does, nutrients in the organic matter are released into the soil. • Decomposers play a vital role in ecosystems. They help put nutrients back into the ecosystem so that they can be recycled by producers. • Without decomposers, nutrient cycles would be incomplete.

  15. Food Chain • Food chains show the feeding relationship between trophic levels. It starts with producers and ends with the last consumer. • Identify the trophic levels in the food chain below

  16. Food Web • Ecosystems have several species that often eat more than one type of food and have more than one predator. • For example, the fox’s prey is the squirrel, the hare, and the grouse. Its predator is the lynx. The lynx’s prey is the fox, and also the squirrel and the hare. The relationships are complex and intertwined. • Therefore a food web is used to illustrate these complex relationships.

  17. Food Chain vs. Food Web • A food web is actually several food chains woven together • Look at the food web in the last slide. Identify the multiple food chains starting with the white spruce as the producer.

  18. Energy and Trophic Levels • When a consumer eats another organism, does it absorb all of its energy? • Example: If a caterpillar eats 100 J of leaves, does it retain all of the 100 J? • If yes, if a bird eats the caterpillar, does it then retain all the 100 J from the leaves? • The answer to both is no. • In fact, the caterpillar would only retain 10 J of the leaves. And if the bird ate the caterpillar, it would only retain 1 J of the energy from the leaves.

  19. What happens to energy? • When one organism consumes another organism, here is what happens to the energy: • 60% of the energy cannot be used and is passed through waste • 30% of the energy is used to for cellular respiration (keeps the body running) • 10% of the energy is used to make new body tissues • Therefore, only 10% of the energy is retained in its body.

  20. What happens to energy • This caterpillar ate 100 J of the leaf. However, only 10 J got stored as body tissue. • Therefore, when a bird eats the caterpillar, the bird will only get 1 J of energy that came from the leaf. • When a fox eats the bird, the fox will only get 0.1J of energy that originally came from the leaf.

  21. Energy and Trophic Levels • Therefore, the caterpillars need to eat a lot of leaves to get enough energy in its body…. And then the birds would need to eat a lot of caterpillars to get enough energy in its body….. And then the foxes would need to eat a lot of birds to get enough energy in its body.

  22. Energy Pyramid • Energy pyramids show the amount of available energy at each trophic level • The more trophic levels that exist in a food chain, the less energy there is left from the original amount at the bottom.

  23. Energy Pyramid • Only 10% of energy can be passed up to the next trophic level • Therefore, in food chains, there has to be more producers than primary consumers, more primary consumers than secondary consumers, and more secondary consumers than tertiary consumers. • As you move up the food chain, there are fewer and fewer organisms. This is why it’s called a food pyramid, because it gets smaller and smaller at the top.

  24. Energy Consumption • Which consumes more energy? An herbivore or a carnivore? • A carnivore. • When an herbivore consumes 1000 J of plants, that’s all in consumes. • However, when a carnivore that consumes 1000 J of prey, the prey had to consume 10000 J of plants. So the carnivore indirectly consumes 10x more energy! • Given this knowledge, can you explain what would happen if the number of secondary and tertiary consumers increased in an ecosystem? (e.g. if the number of foxes and lynx increased).

  25. Niches • Ecosystems are kept balanced so that there aren’t too many primary consumers, and in turn fewer secondary consumers, and then even fewer tertiary consumers • To keep a balanced ecosystem, every species has its niche: food, predator, habitat, etc. • Niches reduce competition between species for the same territory and resources. • Top carnivores play an important role. For example, the lynx. If the lynx were to be extirpated in an ecosystem, there would be too many hares. If there are too many hares, they would eat too many plants, not leaving enough food for the rest of the ecosystem. The lynx’s presence ensures there is enough food for lower trophic levels.

  26. What about humans? • Who consumes more food energy? A human omnivore, or a human vegetarian? • The omnivore. Vegetarians consume less energy and have a lower ecological footprint compared to non-vegetarian humans. Vegetarians only eat plants. Omnivores also eat animals, and these animals eat large quantities of plants (or other animals) in order to grow.

  27. Think of it this way. The grain could feed one meat-eater; or it could feed 10 vegetarians.

  28. Homework • Read pp. 28-32 • Answer Questions: • p. 29 #1-4 • p. 35 #1-3, 9, 12-16

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