Cellular Processes

Recall

Just like technical systems, cells

have inputs and outputs

Inputs

An input is something that

must be added into the

system

An input of a cell is therefore

a substance (or energy) that

enters the cell

Outputs

An output is something that is

produced and leaves a system

An output of a cell is

therefore a substance (or

energy) that is released and

leaves the cell

Example 1Plants are able to

absorb sunlight and

carbon dioxide through a

process called

photosynthesis. This

process allows plants to

make sugar and release

oxygen into the air.

Example 1

What were the inputs?

What were the outputs?

Sunlight (energy) and carbon dioxide

Oxygen and sugar

Example 2

A rabbit eats a dandelion

as it grazes in a meadow.

It then settles back into

its den to take a nap

where it slowly breathes

in and out; taking in the

air and breathing out

carbon dioxide.

Example 2

What were the inputs?

What were the outputs?

Dandelion and air

Carbon dioxide

Inputs and Outputs as a Cycle

Sometimes a substance that

is an output for one

organism can be an input for

another.

Inputs and Outputs as a Cycle

Looking at examples 1 and 2, which

substances were outputs for one organism

but input for the other?

The rabbit produces carbon

dioxide as an output and plants

use that as an inputPlants produce oxygen as an

output that the rabbit breathed in

(input)

Let’s look at 2 cellular

processes in more

detail!

Photosynthesis

All cells need energy to grow

Some living things eat other

things to get energy (consumers)

Where do we get our energy?

Food

Photosynthesis

Some living things produce

their own food (producers)

Like plants!

This process is called

photosynthesis

Photosynthesis

Plants use sunlight as a

source of energy to turn

carbon dioxide and water

into carbohydrates (sugars)

and oxygen.

Photosynthesis

Energy comes from the sun

Water is pulled in by the roots

from the ground

Carbon dioxide is absorbed

from the air through the

leaves

Photosynthesis

6CO2+ 6H2O + solar energy → C6H12O6 + 6O2

This is how we get the oxygen we breathe!

Carbon dioxide + water + solar energy

→ glucose + oxygen

Cellular Respiration

The process of breaking down

food molecules with the help of

oxygen to produce carbon

dioxide and water

This process also releases

cellular energy (ATP) that can

be used by the cell

Photosynthesis vs Cellular Respiration

Photosynthesis:

CO2+ water + solar energy → sugars + O2

Cellular Respiration:

sugars + O2 → CO2+ water + energy

Opposites!

How do these substances

move into (inputs) and out

(outputs) of the cells?

Diffusion

Diffusion:

Movement of particles from

an area of high concentration

to an area of low

concentration

DiffusionThink back to the egg experiment

we did in class, the same thing will

happen with a cell

Substances (solutes) will move

across the membrane from high

concentration to low concentration

until they reach equilibrium

Diffusion

Osmosis

When the substance undergoing diffusion is water, we call the process osmosis

The water will move across the membrane to establish equilibrium

Osmosis

For both diffusion and osmosis,

movement across the

membrane continues until the

concentration is the same on

both sides

Osmosis

Low

sugar

High sugar concentration

Which way will the WATER move?

Low water concentration

High

sugar

Low sugar concentration

Which way will the WATER move?

High water concentration

WorkbookRead:p.61-65, p.68-69, p.

71-73

Practice: p.66-67, p.70,

p.74-75