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Course: Middle school biology > Unit 1
Lesson 1: Cells and organismsIntroduction to Middle school biology
In this course, you'll explore the fascinating world of living things. Learn about cells, organisms, and ecosystems, all while gaining a deeper understanding of your place in Earth's web of life. Created by Sal Khan.
Want to join the conversation?
- why don't we know everything about life yet?(30 votes)
- Because there is so much to life. If we knew everything about life we would probably be super advanced(24 votes)
- How can a gorilla get enough nutrients from only plants?(13 votes)
- Gorillas get enough nutrients from only plants because plants have protein too! That's where all animals get their nutrients. Herbivores get their nutrients from plants and do get enough to survive, and carnivores get their nutrients from the animals that eat the plants. Omnivores do both. Hope that helps!(16 votes)
- If energy is neither created or destroyed, what happened during the big bang?(7 votes)
- The big bang event was a period of rapid expansion of space itself (rather than the creation of 'stuff') from a universe that was hot/dense, to a one that is cooler/more dispersed, with energy 'condensing' into basic forms of matter (I think).
Space is still expanding now, but forces such as gravity keep 'stuff' held together. On a large enough scale, we can see galaxies all generally getting further away from each other in all directions, and the further away they are, the faster they are receding.
Whatever existed before the big bang is an unknown.(10 votes)
- Bio means life and ology means the study of something in Greek. The study of life.
Nicholas(9 votes)
- the true question of life: how to easily make friends(8 votes)
- get a life to have friends(1 vote)
- why don't we know everything about life.(3 votes)
- In my opinion I think it would be impossible to know everything about life. We haven't explored all of earth so there could be unknown life waiting in the most hidden of places. We still don't even know how life even started! Some of it is due to technology that hasn't been invented yet, maybe a time machine will be invented and we'll see the beginnings of live itself.
We also haven't explored all the planets in the universe. Maybe out there, there are silcon based life forms, or animals made of water, or something we can't even imagine. Unless we develop a teleporter or some other amazing technology I don't think we can ever know everything about life.(8 votes)
- the one piece the one piece is real(4 votes)
- The one piece is real!(2 votes)
- how do gorillas get anufe nutrance(3 votes)
- The secrets of life(2 votes)
- I'm a fourthgrader. 'u'(1 vote)
Video transcript
- Hi, everyone. Sal Kahn here. And welcome to Middle School Biology. I have Iman Howard here, who
manages our STEM content. Welcome, Iman, and why should folks care about middle school biology? - Biology is the study of life. And so, in this course, it really answers why are things the way they are, why do you look the way they do, why do I look the way I do, and how every organism on Earth has a really special
purpose and a special trait. And based on these traits, it helps them interact with their environment. We even talk about energy. And energy can't be created
and it can't be destroyed. It actually cycles as
matter through an ecosystem. And it even has this really
cool chemical reactions called photosynthesis, where
plants use light energy from the sun and they make
their own food, which is insane. I think about organisms like
the gorilla that are super-big and strong and they
don't go and eat a cow. They go and eat plants because
that's like getting energy right from the source. And then finally, we talk about evolution. Based on our traits, how
have we changed over time? And how some of our natural
traits were selected by the environment that
create those changes or even how humans, we
have something called artificial selection, which
explains why your dog's so cute. Whether it's 100 pounds or
five pounds, we did that. What do you think's cool about it, Sal? - Oh, well, you know,
biology's trying to answer, I mean, to your point,
the questions of life, which we still don't
understand a lot about but like what makes us us and
to realize that we don't exist as human beings in isolation. We're part of an ecosystem. We're part of a story, a
narrative that's been going on for millions and billions of years. The fact that we're made
up of trillions of cells, each of them with DNA that
can describe who we are, how did all of this complexity come about? This is maybe the most mind-blowing topic that we're really at just the
beginning of this journey. So I think folks are gonna be really, really excited to or it's
gonna be really interesting to see all of the things
that they get to learn. - Well, let's dig in. (enthusiastic chiming)