Chapter 1From Cells to Ecosystems

Lesson 1Cells

What are cells?

An organism is a living thing made of the same tiny building blocks.

A cells is the smallest unit of living things that can carry out the basic processes of life.

A unicellular organism is made of a single cell that carries out its life processes.

An amoeba is unicellular organism.

Multicellular organisms are made up of more than one cell.

What is inside an animal cell?

Plant and animal cells have several basic structures, called organelles, that help them perform life perform life processes.

The cell membrane is a layer around the outside of the cell.

The cell membrane gives the cell its shape.

The cell membrane controls what materials move into an out of the cell.

Cytoplasm is a gel-like liquid that fills the region inside the cell membrane.

The cytoplasm supports all the cell’s structure.

The nucleus is the cell’s control center.

The nucleus is a large, round organelle found in the center of the cell.

The nucleus sends signals to all other parts of the cell.

Mitochondria are oval, membrane-covered organelles that supply energy for the cell.

Mitochondria break down food, which releases energy for the cell to use.

A vacuole is a membrane-covered structure used for storage.

Vacuoles store water, food, and wastes.

What is inside a plant cell?

Plant cells have many of the same structures and organelles as animal cells, but there are some additional organelles that animals cells do not have.

Plants have a stiff structure outside the cell membrane called the cell wall.

The cell wall gives the plant cell extra strength and support.

Vacuoles store excess water and provides extra support.

Plants make their own food in structures inside their cells called chloroplasts.

Chloroplasts is a green structure where the energy from sunlight is used to produce food for the plant.

Chloroplasts are green because they contain chlorophyll.

Chlorophyll is able to use the energy in sunlight.

Chloroplasts are mostly found in leaf and stem cells.

How are cells organized?

Similar cells working together at the same job form a tissue.

A group of tissues that work together to perform specific function form an organ.

Organs that work together to perform a certain function make up an organ system.

Lesson 2Relationships in an Ecosystem

What is in an ecosystem?

Living things in an ecosystem are called biotic factors.

Examples of biotic factors are plants, trees, animals.

Nonliving things in an ecosystem are called abiotic factors.

Examples of abiotic factors are water, soil, rocks, and air.

What is in an ecosystem?

An ecosystem includes all living and nonliving things in an environment.

The organisms an ecosystem are separated into populations.

A population is all the members of a single species in an area at a given time.

Example: All the blue spruce trees in a forest are one population.

What is in an ecosystem?

All of the populations in an ecosystem can be put together to make up a community.

One community could include thousands of populations.

How are food chains alike?

The path that energy and nutrients follow in an ecosystem is called a food chain.

Food chains are the feeding relationships in an ecosystem.

All of the energy in a food chain starts with the Sun.

Producers are organisms that use the Sun’s energy to make their own food in the form of sugar.

How are food chains alike?

Plants are producers.Producers have the most energy

in a food chain and are at the base of an energy pyramid.

A consumer is any animal that eats plants or other animals.

A primary consumer is a consumer that eats the producer.

How are food chains alike?

A secondary consumer is the consumer that eats the primary consumer.

Herbivores are consumers that eat only producers.

Examples of herbivores: squirrels, some birds, grazing animals.

Carnivores are consumers that eat other animals and not producers.

How are food chains alike?

Examples of carnivores: hawks, lions, panthers.

Omnivores are consumers that eat both plants and other animals.

Examples of omnivores: raccoons, humans, mice.

Scavengers are consumers that eat leftover bodies after they have started to rot.

How are food chains alike?

Vultures and raccoons are examples of scavengers.

Decomposers are at the end of a food chain and they break down dead or decaying plants and animals.

Fungi, bacteria, worms, and termites are all types of decomposers.

What are food webs made of?

A food web is a network of food chains that have some links in common.

To read a food web, the arrow points to what eats the other organism.

A predator is an animal that hunts other animals for food.

Prey are organisms that are eaten by other animals.

What are food webs made of?

Predators are important in food webs because they keep the prey population smaller so resources do not run out in an ecosystem.

What are symbiotic relationships?

Interdependence is the reliance of certain organisms on other organisms for their survival.

Symbiosis is a relationship between two or more organisms that lasts over time.

There are 3 types of symbiotic relationships: mutualism, commensalism, and parasitism.

What are symbiotic relationships?

Mutualism is a relationship where both organism benefit.

Example of mutualism: a pollinator and a flowering plant. The pollinator gets nectar from the plant and the plant gets the pollen transferred to another flower.

Commensalism is a relationship that benefits one organism without harming the other.

What are symbiotic relationships?

Example of commensalism: remoras and sharks. Remoras get food scraps, transportation, and protection. The remora does not help or hurt the shark.

Parasitism is a relationship where one organism benefits and the other is harmed.

A parasite lives in or on a host organism and benefits from the relationship.

What are symbiotic relationships?

Example of parasitism: ticks and dogs. Ticks are the parasite that feeds on dogs, which are the hosts.

Lesson 3Photosynthesis

What is photosynthesis?

Sunlight is a form of energy that plants use to make their food.

Photosynthesis is the process of making food using sunlight.

Photosynthesis only happens in cells that have chloroplasts.

What is photosynthesis?

Sunlight, water, and carbon dioxide are needed to perform photosynthesis.

The end result of photosynthesis is sugar and oxygen.

What do leaves do?

Leaves have the job of carrying out photosynthesis.

Water is absorbed through the roots.

Carbon dioxide enters the plant through the air into the stomata.

Stomata are tiny pores on the underside of the leaves.

What do leaves do?The stomata are opened and closed

by two guard cells.The guard cells open and close the

stomata in response to the amount of water and light the plant receives.

If the plant has too little water, the guard cells close the stomata. If it has too much water, the guard cells open the stomata and let out water.

What do leaves do?Photosynthesis occurs in

chloroplasts in the epidermis.The epidermis is the outermost layer

of a leaf.The top leaf surface has a waxy

cuticle, a waterproof layer that prevents moisture from evaporating.

Carbon dioxide + water ------- sugar + oxygen

What is the photosynthesis and respiration cycle?

The sugar produced in photosynthesis is a carbohydrate.

A carbohydrate is a group of substances made from carbon, hydrogen, and oxygen.

Animals take in these carbohydrates when they eat a plant.

What is the photosynthesis and respiration cycle?

Oxygen that is produced by photosynthesis is breathed in by animals during repiration.

The energy in carbohydrates is released when the cells of organisms use oxygen to break down the sugars in the process called cellular respiration.

What are energy pyramids?

An energy pyramid is a diagram that shows the amount of energy available at each level of an ecosystem.

The bottom of the energy pyramid is producers.

There are fewer numbers of organisms and less energy the higher the level in the pyramid.

Lesson 4Changes in Ecosystems

How can ecosystems change?

Ecosystems can be changed by natural events or by living organisms.

Natural events include natural disasters such as earthquakes, floods, storms, hurricanes, volcanoes, and drought.

People can try to repair the damage from natural disasters, but they cannot prevent them.

How can ecosystems change?

Animals can change ecosystems by building homes.

A population can grow out of control causing harm to other populations.

Human can introduce new organisms to an environment causing threat to those native species.

How do people affect the environment?

Pollution is a harmful change to the natural environment.

How people affect landStrip-mining: removing the topsoil

from dirt to remove minerals. The topsoil has all of the nutrients which wash away into lakes and streams.

When crops are harvested, there is very little nutrients left in the soil for future crops.

How do people affect the environment?

Trees are cut downRoads bring more vehicles which let

off gas and leak oilHow People Affect Water and Air

Factories dump waste and chemicals into lakes and rivers

Oil leaks from shipsFertilizers and pesticides soak into the

ground or flow into lakes and rivers, harming fish, birds, and mammals.

How do people affect the environment?

When people burn fuel to power factories, heat homes, or drive vehicles, air pollution is produced.

Smog is a combination of smoke and fog that can irritate eyes, nose, and throat

Acid rain occurs when air pollution mixed with moisture in the atmosphere.

Acid rain pollutes water and soil, kills plants and fish, and damages stone and metal.

How does waste affect the land?

Most of the garbage ends of in landfills

Household garbage may contain harmful substances

Some garbage is biodegradable, or able to break down naturally over a short period of time.

Other garbage is nonbiodegradable and can build up over time.

How does waste affect the land?

Toxic waste must be disposed of carefully so it does not pollute the soil, groundwater, rivers, and lakes.

Common household items can contain hazardous components

Three Rs of conservation: reduce, reuse, and recycle.

How does waste affect the land?

We can reduce the amount of natural resources we use.

Reusing materials saves resources.

We can recycle materials to make them into other products.

What happens when ecosystems change?

Organisms must respond to these changes in order to survive.

Some organisms migrate to a place where they are more likely to survive.

Other organisms respond by adapting to ecosystem changes.

Individual species could begin to die.

What happens when ecosystems change?

Extinct species are organisms that have completely died out.

When a species is in danger of becoming extinct, it is called an endangered species.

Species with low numbers that could become endangered are called threatened species.

What happens when ecosystems change?

Pollution, overhunting, disease, and competition from newly introduced organisms can cause a species to die out.

The biggest threat to the survival of most organisms is habitat loss.

How do ecosystems come back?

The process of one ecosystem changing into a new and different ecosystem is called succession.

Primary succession takes place in a community where few living things exist, or where earlier communities were wiped out.

Primary succession occurs in barren, lifeless areas that have little or no soil.

How do ecosystems come back?

Pioneer species are the first species living in a lifeless area.

A climax community is the final stage of succession.

What is secondary succession?

Secondary succession is the beginning of a new community where another community previously existed.

Secondary succession occurs faster than primary succession.