Chapter 4 SECTION 2 - Populations

1 Each organism in an ecosystem needs a place to live called habitat. The habitat provides everything an organism needs to SURVIVE AND REPRODUCE: Food, water Shelter Habitats Adequate temperature and humidity

Organisms are not alone An ecosystem consists of all the organisms living in an area, as well as the nonliving parts of that environment. Different types of organisms living in the same area will interact.

2 Populations One of the most important aspects related to the interaction among organisms is called COMPETITION Competition occurs when two organisms seek the same resource at the same time.

2 Populations Competition will: 1) Decrease an organism s chance of survival 2) Limit population growth

In nature, the most intense competition is usually among individuals of the same species, because they need the same kinds of resources.

1) What do organisms living in the same area will compete for? Food, space, water, light (plants), organisms of the same species to mate

2) What is population density? Book page 99 Population size It is the number of individuals of one species Per a specific area

3) Why is it important to measure the size of different populations on a given environment? -To make sure the species is not in danger of disappearing of that area -To determine hunting seasons -To determine how many organisms can be removed from the ecosystem - The size of this organisms Ex. Crabs

4) What methods can be used to measure population size? 2 methods that are widely used: First method : Sample Counts Read page 100 Figure 7

Sample Counts EX: A biologist collected 1 gallon of pond water and counted 50 paramecium (unicellular organisms). Based on the sampling technique, how many paramecium could be found in the pond if the pond were 1,000 gallons? 50 x 1000 = 50,000

**Problem with the Sample Count Technique - different areas might have more dense populations if you took a sample from the bottom of the lake it may be different from a sample at the top of the lake

Measuring Population Size Second method: Trap, Mark and Release or Mark and Capture - estimates the number of organisms in a population **This technique is commonly used by fish and wildlife managers to estimate population sizes before fishing or hunting seasons. worksheet

Problems with the Mark- Release Make sure: Technique There is no immigration or emigration Animals are mixing with the rest of the population in between samplings Mark them well or they will loose the mark The period of time in between samplings have to be smaller than the life span

Aspects that affect the size of a population Birth rates and death rates Immigration and Emigration ( organisms can be carried by wind, water, or just move on their own) Limiting factors

Important terms Find the definitions of: Limiting factor Carrying capacity Biotic Potential

2 Populations Limiting Factors living or non living A limiting factor is anything that restricts the number of individuals in a population. Ex: availability of food, water, living space, mates, nesting sites ( shelter), light (plants), predators

2 Populations Limiting Factors A limiting factor can affect more than one population in a community, at the same time Ex: Lack of water,will affect different populations lack of light for plants

2 Limiting Factors Visualizing the effect of a limiting factor in a population Worksheet to turn in graph paper and ruler The Lynx Hare relationship over the years reflect how the predator /prey interaction of two species affects population size.

The lynx eats the hare so if there are not enough hares, the number of lynx will decrease. The number of hares limits the lynx population. The hare is killed by the lynx, so if there are few lynx, the population of hares will increase.

2 Carrying Capacity of an Ecossystem is the largest number of individuals of one species that an ecosystem can support over time. If a population begins to exceed the environment s carrying capacity, some individuals will not have enough resources and competition will increase. die move elsewhere.

2 Biotic Potential It is the highest rate of reproduction in a population, under ideal conditions Ideal Conditions would be: No diseases No predators, Enough food, water and space ( no competition)

2 Populations Exponential Growth When a species moves into a new area with plenty of food, living space, and other resources, the population grows quickly, in a pattern called exponential growth. Exponential growth means that the larger a population gets, the faster it grows.

2 Populations Exponential Growth Over time, the population will reach the ecosystem s carrying capacity for that species and will stop the exponential growth.

Humans Exponential Growth Does Earth have a carrying capacity?

The S curve shows the normal pattern followed by a growing population

Book page 105 questions 1-4 Workbook page 12

Section 3 Interactions within Communities about feeding patterns within a community and how the energy moves from one organism to another Guided reading

1) Organisms obtain energy by the process of photosynthesis or cellular respiration. Define: 1a)Producers 1b)Consumers Explain which one uses photosynthesis and which one uses cellular respiration and why.

2) Explain the difference between the 4 types of consumers. 3) what is a food chain and what is food web see Glossary 4) What is symbiosis? List 3 types of symbiosis and explain.

5) what is niche? 6) Why does each species have its own niche, and why is this important in an ecosystem? 7) Explain why a predator-prey relationship can be important in an ecosystem. 8) Why is cooperation among organisms important?

3 1 - Obtaining Energy Living organisms need a constant supply of energy to survive. There are 3 types of processes used by organisms to obtain E. 1) Photosynthesis 2) Chemosynthesis 3) cellular respiration

3 1a- Producers: Organisms that use an outside energy source like the Sun to make energy-rich molecules Green plants are producers they have chlorophyll and will transform water and carbon dioxide into sugars, in the presence of light. The process is called photosynthesis

Chemosynthesis another chemical process used by organisms to produce energy rich nutrients. It is used by organisms that do not have access to light such as bacteria that live close to the ocean floor.

Chemosynthesis These organisms use energy obtained from chemicals to replace the sunlight energy used during photosynthesis. Chemosynthesis is thought to have been used by the first forms of life on Earth.

Interactions Within Communities 1b - Consumers Organisms that cannot make their own energy-rich molecules because they do not have chlorophyll. Consumers obtain energy by eating other organisms ( producers or consumers) and use cellular respiration to break the food and obtain E.

Oxidation = Cellular Respiration Cellular Respiration is an oxidation process. It is a chain of chemical reactions that happens in the presence of Oxygen.

2) Explain the difference between the 4 types of consumers.

Interactions Within Communities 2 - Consumers: 4 types Herbivores eat plants Carnivores eat meat Omnivores eat plants and meat Decomposers consume wastes and dead animals

3) what is a food chain and what is food web see Glossary for food web

3 - Food Chain model that shows the feeding relationships in an ecosystem and the path of the energy. The arrow points to the predator For example, shrubs are food for deer, and deer are

Food web is a complex model shows the connections among different organisms in different food chains The arrow points to the predator

4) What is symbiosis? List 3 types of symbiosis and explain. Mutualism Commensalism parasitism

3 4 Symbiosis It is the term used to describe any close relationship between species. Sometimes one species depend on another to survive There are 3:

a) Mutualism both organisms benefit from this association.

3 Lichens association between algae and a fungus Cyanobacteria or algae will produce food for the fungus Fungus provide shelter or a place to live to the cyanobacteria

Bees and hummingbirds obtain food but also spread the pollen of the plants

3 b) Commensalism - A symbiotic relationship in which one organism benefits and the other is not affected

Anemones and Clown fish The anemone s tentacles protect the clown fish from predators.

Shark and Remora: Commonly called a suckerfish, the remora is a marine fish that attaches to the shark and feeds on sharks left overs.

3 c) Parasitism - a symbiotic relationship in which one organism benefits but the other is harmed

Roundworms Are parasites that attach to the inside of the intestines of other organisms and feed on these organism s blood.

Dodder wraps itself around the stems of other plants damaging the plant

5) what is niche?

5- Niche An organism s niche is its role in its environment: - how it obtains food - or shelter, - or a mate, - or cares for its young - what they eat, where they live, etc.

6- Why does each species have its own niche, and why is this important in an ecosystem?

5- Niche The niche of each species that live in the same area is a little different to avoid competition. So it is important that different species have different niches Examples:

Closely-related species will: Have different food preferences, Hunt for food at different times, Live in different locations within the area The niches are a little different so the different species can live in the same area

It is important because it allows different species to inhabit the same place, bringing diversity to the area.

7) Explain why a predator-prey relationship can be important in an ecosystem.

7- Predator and Prey Importance for the Ecosystem: The predator will limit the size of the prey population As a result, food and other resources used by the prey will not be scarce the population of the prey in that area will remain somehow constant and, the predator will be able to continue feeding on the prey

Is a predator and prey relationship a type of symbiosis? **Predator Prey is different than symbiosis because one organism will die for the other to survive. In symbiosis both will live

8) why is cooperation among organisms important?

8- Cooperation Individual organisms often cooperate in different ways. Cooperation improve survival and it is part of a specie s niche For example, a white-tailed deer that detects the presence of wolves or coyotes will alert the other deer in the herd. Social organization of insects different tasks

Textbook page 110 questions: 1, 3 and 4 Workbook page 13

Chapter 5 Sections 2 and 3

Matter and Energy Flow In nature, energy and matter are never lost, they just change from one form to another and are transferred from one organism to another. Food Chains and Food Webs are models that illustrate these transfers.

Food Chains - is a simple model of the feeding relationships in an ecosystem. It shows how energy is transformed in nature and how is transferred from one organism to another.

Food Chains A food chain always starts with the producers or autotrophs ( can make its own food the others are called heterotrophs) The second step are the herbivores or primary consumers The third step are the secondary consumers that will eat the primary consumers or herbivores. The tertiary consumers eat the secondary consumers. They can be carnivores or omnivores. Decomposers

A food chain always starts with the producers or autotrophs ( can make its own food the others are called heterotrophs)

Decomposers play an important role: Decomposers complete the food chain and will return nutrients from the decomposed dead plant or animal, back to the environment.

Food Web: model that shows the complex feeding relationships in a community. It is complex because it shows how different food chains are interconnected. Different consumers eat diff. types of foods

The arrow points to the organism that is obtaining the energy

Trophic Levels The position of an organism within a food chain or food web are called trophic levels. These levels are divided into: producers (first trophic level), consumers (the following trophic levels), decomposers (last trophic level).

T r o p h I c L e v e l

Energy transfer and Energy loss Both Food Chain and Food Web show how energy is transferred from one trophic level to another. IN each one of the trophic levels, organisms will oxidize their food to obtain energy to survive. From one level to another some energy is lost to the environment in the form of heat.

Energy Pyramids Shows the amount of energy available in each trophic level. The first trophic level is the base of the pyramid, with more organisms and more energy available.

% of energy left from one trophic level to another

Textbook page 139 question number 3 Workbook page 17

Biotic and Abiotic Factors Biotic and Abiotic are important parts of an ecosystem. Some abiotic factors are: water, atmosphere and soil They are important because they contain substances that are indispensable for the survival of any organism.

Cycles in Nature The Earth contains a fixed amount of water, carbon, nitrogen and oxygen; materials required for life. Theses materials cycle through the environment and keep on being reused by different organisms

Important Cycles Water cycle Oxygen cycle Nitrogen cycle Carbon Cycle

Oxygen Cycle In your own words, write a paragraph describing the Oxygen cycle. Think about: plants, photosynthesis, animals, respiration. Time: 5 min

Oxygen Cycle plants ( autotrophs) take in CO2, water and produce O2 in the presence of sunlight. The O2 is released in the atmosphere O2 is taken in by heterotrophs during respiration, transformed in CO2 during cellular respiration. It is released in the atmosphere by the heterotrophs and absorbed again by plants.

Nitrogen Cycle 78% of the atmosphere is Nitrogen But the N2 in the atmosphere can t be used by organisms

Organisms can t absorb nitrogen from the atmosphere Molecules of Nitrogen are two atoms of nitrogen united by a stable triple bond. This bond must be broken for the nitrogen to be used. The nitrogen gas must be changed to nitrogen compounds called nitrates or ammonia, to be absorbed by organisms.

Nitrogen Cycle-Book page 132 1) Why is Nitrogen important for organisms? 2) Explain Nitrogen Fixation 3) Explain the Nitrogen Cycle or make a diagram 4) Explain why farmers use fertilizers or plants with nitrogen fixing bacteria. 5) What type of symbiotic relationship exists between the bacteria and the roots?

1) Why is Nitrogen important for organisms? Proteins and DNA contain N2 and organisms depend on these two types of molecules to survive

2)Explain Nitrogen Fixation - Some bacteria can absorb N2 from the atmosphere and transform this N2 in the Nitrogen compounds that can be used by plants. - Those are the nitrogen-fixing bacteria that live inside the roots of some plants and in the soil

Other important bacteria involved in the N cycle ( copy) Nitrifying bacteria turn the Nitrogen in wastes and dead organisms ( ammonia) into nitrates Denitrifying bacteria turn the nitrates into N2 ( nitrogen molecules) and return them to the atmosphere

Nitrogen Cycle 3) Explain the Nitrogen Cycle or make a diagram

Nitrogen Cycle 4) Explain why farmers use fertilizers or plants with nitrogen fixing bacteria. When soils is over used, the level of nutrients decrease. To add nutrients to the soil and make sure the soil is fertile, farmers use fertilizers, manure, compost or plant with nitrogen-fixing bacteria

5) What type of symbiotic relationship exists between the bacteria and the roots? Mutualism: It is advantageous for both species. The bacteria depends on the plant for food and the plant depends on the bacteria to obtain N2

Carbon Cycle Carbon is also very important for any organism survival.

Carbon Cycle 1) Read page 66 of the textbook and explain why is carbon important and where is carbon found in our body. 2) Look at the picture on page 134 and explain what the sources of carbon and carbon dioxide are. 3) Make a drawing or a diagram of the Carbon Cycle

1) carbon is found in organic substances such as: carbohydrates, lipids, nucleic acids and proteins. Organisms are made of these substances Organisms are also dependent on carbon dioxide that is an inorganic compound that contains carbon, too.

Carbon Cycle 2) Look at the picture on page 134 and explain what the sources of carbon and carbon dioxide are.

2) burning of fossil fuels releases carbon dioxide Organisms cellular respiration to break sugars releases carbon dioxide in the atmosphere organisms decay after death releases carbon in the soil and carbon dioxide into the atmosphere

Carbon Cycle 3) Make a drawing or a diagram of the Carbon Cycle

Textbook page 135 questions 2 and 4 Workbook page 16

End of Chapter Summary File