Introduction to Science 10

What is science?• Brainstorm: What is science?

What is science?• Science is the study (or way of looking at) the

natural (or “not made by humans”) world around us.

• There are many different types of science, including biology (the study of life), chemistry (the study of matter) and physics (the study of matter & energy, and the interaction between them)

Science 10Unit 1: Sustainability of

Ecosystems

Anticipation Guide for Science 10

What is an ecosystem?• An ecosystem includes all organisms in an area

that interact with each other and with their environment of energy and matter.

• In other words, all plants, animals, bacteria, fungus, etc. in an area interact and connect with each other AND with the environment.

Examples of Ecosystems• Swamps & marshes• Freshwater lakes, ponds & streams• Saltwater lakes & coastal ocean• Temperate forests• Highland forests

Unit Overview with Youtube Song

Key Concepts

• The Sun is the ultimate source of energy for most ecosystems

• Light energy from the Sun is converted by plants into chemical energy

• Energy is channelled through the food chains

Assignment 1: You and Food Chains

• Complete the handout and submit to your teacher

Student Guide• Introduction: The Importance of Respect• Explanation of how student guide will be

assessed• Work on Check Your Understanding (pg 2)• Did not do this as of yet!!!!

DefinitionsDefine the following terms:• Herbivore• Carnivore• Omnivore• Trophic level• Primary producer• Primary consumer• Secondary consumer• Tertiary consumer• Decomposers

Assignment 3: Food Webs• Create a food web

Questions• Check Your Understanding; pg 7; #1-5

Food Pyramids• Food chains are often too simplistic and do

not provide a completely accurate picture of an ecosystem. A better way to look at the ecosystem is to make use of food pyramids.

• There are three types of food pyramids:1. Pyramid of Numbers2. Pyramid of Biomass3. Pyramid of Energy (the best!)

Pyramid of Numbers: Where do these organisms fit?

Thousands or millions of producers

1-2 top carnivores

What is a pyramid of numbers?• A pyramid of numbers shows that in most

ecosystems, there are more producers than herbivores (or primary consumers) and more herbivores than carnivores (secondary and teritary consumers).

• But, this is not true for all ecosystems.• Let’s take a look at the ecosystem within a

single oak tree:

Looks unstable...

But it’s not!!!!

Pyramid of Biomass• A pyramid of numbers does not take into

account the size of the organism, just the number.

• A better way of looking at an ecosystem is to use a pyramid of biomass. Biomass means how much mass (or weight) is at each level.

But, still some problems..

Pyramid of Energy• The best type of pyramid is a pyramid of energy.• A pyramid of energy flow measures the total

amount of food energy that flows through each trophic (or feeding) level.

• Basically, there is always less energy available for each level as you go UP the pyramid.

• Also, it is impossible to turn a pyramid of energy upside down.

Pyramid of Energy of Flow

What does a pyramid of energy show?

• Probably the most important thing to understand about a food pyramid is that only about 10% of the energy makes it from one level to the next.

• Why does this happen? Energy is lost because of a variety of reasons, including:

1. Movement2. Digestion3. Thinking4. Growing5. Reproduction

Questions• Check Your Understanding• Pg 17; #1-5

ORFINISH FOOD WEBS!!!

Assignment #4• Work on Bioaccumulation: The DDT Story

What is primary productivity?• Primary productivity is the average amount of

new plant material (or biomass) that is added to an ecosystem per year.

• Primary productivity is measured as the amount of energy per square metre per year (or kJ/m2/year)

• The most productive ecosystems include rain forests and salt marshes, while the least productive would be deserts.

How do plants make food?

sugar

What goes in?

What goes out?

How do plants make food?• All green plants & seaweed make food using a

process called photosynthesis • Photosynthesis is a process used by plants to

convert (or change) light energy from the sun into sugar. This sugar is used by the plants for energy.

• These sugars are made from water and carbon dioxide (CO2). Oxygen is released as a waste gas.

• Photosynthesis provides oxygen to the atmosphere and supplies most of the energy for life on Earth.

Photosynthesis Reaction Equation

• A chemical called chlorophyll makes this reaction possible. Chlorophyll gives leaves a green colour.

• The photosynthesis equation is probably the most important reaction for all life on Earth!!!

Simplified Photosynthesis Equation

These go into the plant cells. These come out of the plant cells.

Primary Productivity of Various Ecosystems

The MOST PRODUCTIVE ecosystems are salt marshes, swamps and tropical rain forests.

The LEAST PRODUCTIVE ecosystems are the tundra, open ocean and deserts.

Global Primary Productivity

DESERT

ARCTIC

ARCTIC

RAINFOREST

TEMPERATEFOREST

What do plants need to grow?

What are humans supplying to these plants?

Nice rain forest....NOT!!!

How many people can Earth support?

• Read the article• Keep in mind that the Sun can only provide

the Earth with so much energy. And, the Earth only has so much usable land.

• BTW, Earth grows 4.2 million hectares of tobacco compared to 3.7 million hectares of tomatoes. Is this a good use of land?

Examples of Populations • A group of birch trees living on a hill• A colony of 2,146 ants • All of the spruce trees in a forest• All of the cod fish in the Bras d’Or Lake• Frogs living in a pond

What is a population?• A population is a group of organisms of the

same type (or same species) living in the same area.

• A population is usually the actual number of individuals in an area that are all the same type.

What is the population?

What makes a population get bigger in number?

• More births than deaths• Moving into an area from somewhere else• Lots of food & water• No disease• Good weather

What makes a population get smaller in number?

• More deaths than births• Moving out of an area• Disease & sickness• Severe weather, droughts & storms• Starvation or lack of food

Can any population keep growing forever?

• NO!!! The largest population that an environment can support is called the carrying capacity.

• For example, a forest ecosystem may only be able support a few dozen deer.

What might limit the numbers of a population?

1. Materials & energy (sunlight, water, fertilizer, etc.)

2. Food chains (the amount of food lower in the food chain)

3. Competition (between same species or different species)

4. Overcrowding (leading to not enough space, disease, less births, more deaths, etc.)

5. Natural disasters (such as forest fires, storms)

Define the following words(Pgs 18-20 & glossary)

• Natality• Mortality• Population size• Population density• Immigration• Emigration• Intraspecific competition• Interspecific competition

Answer these questions1. What is meant by the term “carrying capacity”?2. How might overcrowding lead to a reduction in

population size?3. How might an increase in population of plants

in an area lead to an increase in the population of hawks?

4. How might an increase in the population of hawks in an area lead to an increase in the population of plants?

Assg 5: Googles & Gaggles• Work on the activity in class• This is an in-class assignment worth 10 points• You will be evaluated on how well you work

and on getting some good numbers!!

Cycles of LifeWhat are nutrients?Nutrients are chemicals used by organisms (plants, animals, fungus, bacteria) to operate their bodies. Nutrients include non-living nutrients (oxygen, water, carbon dioxide, minerals). Organic (or “living nutrients”) include carbohydrates, fats & proteins.What is a nutrient cycle?A nutrient cycle is the cycling (or recycling) or a nutrients through the environment.

The Carbon CycleWhat is carbon?Carbon is the key chemical or element upon which all life is based. Carbon is one of the most important chemicals in all living things.

What is the carbon cycle?Simply put, plants take in carbon dioxide (CO2) from the air during photosynthesis and make carbohydrates (or sugars). Animals and other consumers then eat the carbohydrates for energy and growth. Also, animals give off carbon dioxide in their breath (as a waste gas). And the cycle continues.

Video

The Carbon Cycle

Overview of Carbon Cycle

Explanation of the Carbon Cycle1. Plants take in carbon dioxide during a process called

photosynthesis.2. During photosynthesis, plants change carbon dioxide to

sugar/carbohydrates and oxygen with the help of sunlight and water.

3. Consumers eat plants (and other animals) for food. These consumers take in sugar/carbohydrates (from plants) during a process called cellular respiration.

4. During cellular respiration, consumers change sugar and oxygen into energy. Carbon dioxide and water are given off as waste products.

5. The cycle repeats. Plants use carbon dioxide during photosynthesis.....

Reactions for Photosynthesis & Cellular Respiration

Photosynthesis

Cellular Respiration

Assignments• Carbon cycle webquest and nitrogen cycle

webquest

Simplified Nitrogen Cycle

Full Nitrogen Cycle

Why is nitrogen important to life?Plants and animals could not live without nitrogen. It is an important part of many cells and processes such as amino acids, proteins, and even our DNA. It is also needed to make chlorophyll in plants, which plants use in photosynthesis to make their food and energy.

Interesting Facts• Around 78% of the atmosphere is nitrogen. However,

this is mostly not usable by animals and plants.• Nitrogen is used in fertilizer to help plants grow

faster.• Nitrous oxide is a greenhouse gas. Too much of it can

also cause acid rain.• Nitrogen has no color, odor, or taste.• It is used in many explosives.• About 3% of your body weight is nitrogen.

What is the nitrogen cycle?• Nitrogen is used by organisms to carry out many of the functions

of life. This element is especially important to plant life. Yet, nitrogen in its gaseous form is almost entirely unusable to organisms. It must first be converted or “fixed” into a more usable form. The process of converting nitrogen is called fixation.

• There are specialized bacteria whose function it is to fix nitrogen, converting it, so that it can be used by plants. There are still other bacteria who do the reverse. That is, they return nitrogen to is gaseous form. This process is called denitrification.

• After nitrogen is fixed, it can be absorbed and used by plants, and then eventually by animals.

• The process of nitrogen being fixed, used by plants and animals, and later returned to the atmosphere is referred to as the nitrogen cycle.

How have humans altered the Nitrogen Cycle?

Unfortunately, human activity has altered the cycle. We do this by adding nitrogen into the soil with fertilizer as well as other activities that put more nitrous oxide gas into the atmosphere. This adds in more nitrogen than is needed by normal cycle and upsets the cycle's balance.

Explanation of the Nitrogen Cycle• Video