Why Do Living Things Need Food?, The Living Organisms and their Surroundings, Class 6 Science Video Lecture

[Intro]
We all eat right?
But have you ever wondered why we eat?
I mean some animals only eat plants, others
just eat other animals, and some creatures
eat both plants and meat.
But the thing is, all animals, including humans,
eat.
And we don't just eat because we're hungry,
or bored, or tired, or it tastes good.
Although I could really go for a slice of
pizza right now.
We eat because we need food to live.
More exactly, we need the energy that food
gives our bodies to grow, move, and stay warm.
You've probably figure this out already from
the things you've heard about how and when
we eat.
Like you've probably heard that breakfast
is the most important meal of the day, or
you might know that runners will 'carb load'
before a big race.
But food is necessary for all living things,
all the time.
You may have noticed that your collection
of cool rocks that you have under your bed,
never needs a lunch of club sandwiches and
baby carrots.
That's because they're nonliving things.
But food is most definitely a necessity for
animals, and plants too.
Even though we don't think of plants as 'eating'
because they don't have mouths, they still
need food to grow and repair themselves, just
like we do.
In fact plants make a nifty model that can
help us understand how the energy from food
affects living things.
To see how food affects plants, we can test
what happens when they get more or less food.
Plants get most of their food from the sun,
water, and carbon dioxide in the air.
More on that another time.
But to test how food affects plants for yourself,
you can use liquid plant food, that way you
can control how much food or nutrients a plant
gets.
So consider this little investigation.
Say you have two little plastic cups filled
with potting soil, and you planted a lima
bean seed in each one, then you give each
plant a different amount of food.
Plant number one will be your control, that
means that you don't give it any additional
food at all, just a little water and sunlight,
and it will do what plants do all on its own.
Then you can make plant two your extra food
plant.
Ask your parents for some liquid plant fertilizer
and add the recommended amount to plant two.
Now it you kept watering and feeding your
plants the same amount for, say, four weeks,
what do you think will happen?
Would you expect both of the plants to grow
the same amount?
Or would one grow more than the other?
If so, which ones?
Well, what you'd find is that plant two grew
bigger than plant one because living things
need food to give them energy, so they can
repair themselves and stay healthy, and in
this case, grow.
So with more food, plant two got more energy,
and that allowed it to grow bigger.
Now got eat your vegetables.