Pratica di Shadowing: How Large Can a Bacteria get? Life & Size 3 - Impara a parlare inglese con YouTube
C2
In and out.
145 frasi
Se le frasi sono troppo corte o troppo lunghe, clicca su Edit per modificarle.
1
In and out.
2
In and out.
3
Staying alive is about doing things.
4
This very second, your cells are combusting glucose molecules with oxygen to make energy available,
5
which keeps you alive for another precious moment.
6
To get the oxygen to your cells, you're breathing.
7
Breathing is an answer to a very hard problem.
8
How do you get the resources that your cells need to survive from the outside to the inside of your cells?
9
Every living thing has to solve this problem
10
and the solution is surprisingly different depending on one of the most important regulators of life, size.
11
As we've discussed in other videos,
12
at different scales the physical laws of the universe have different consequences for its inhabitants.
13
Simple things like temperature, microgravity or surface tension might not matter to you or be a deadly danger,
14
depending on how big you are.
15
Living things need a lot of different materials to keep themselves going.
16
And they somehow need to transport them from the outside to the inside.
17
This was a huge problem for the first things on the verge of being alive,
18
because doing anything in our universe requires energy.
19
And the first living beings on Earth did not have the abundance of tools
20
and techniques available that life has today after billions of years of evolution.
21
So, at the very beginning,
22
life needed to find a way to get good stuff inside and bad stuff outside of itself without using energy.
23
Luckily, the very first forms of life were very, very small.
24
And because they were so small,
25
they were able to use a free form of transport that was based on a physical law called diffusion.
26
Diffusion is the rule of the universe that molecules,
27
especially in liquids or gases,
28
are constantly moving around in all directions.
29
And because they move around and bump into each other and other molecules,
30
they tend to spread.
31
For example, if you drop a sugar cube into water,
32
then there is a lot of sugar in one place,
33
and in another place, there's none.
34
As sugar molecules dissolve in the water,
35
they will start randomly bumping against the water molecules and other sugar molecules.
36
Slowly, all the sugar molecules will spread out and form multiple phases of different concentrations.
37
These random movements continue endlessly until at some point the sugar will be spread evenly in the water.
38
The great thing about diffusion is that life can use it for free.
39
It doesn't require energy.
40
And life loves free things.
41
So all life on earth relies on diffusion.
42
Let's look at the smallest living being on earth, a bacterium.
43
Specifically its surfaces.
44
Cell membranes allow for diffusion of certain molecules.
45
This specific bacterium consumes oxygen to live while carbon dioxide is produced inside as a waste product.
46
So inside the bacterium there isn't a lot of oxygen but a lot of carbon dioxide.
47
Because of diffusion these molecules will eventually spread evenly
48
so the carbon dioxide diffuses out while oxygen is constantly replenished from the outside.
49
But this kind of breathing only works for the very small world,
50
for bacteria, amoeba or your cells,
51
and a few very small animals.
52
Insects, for example, have a fine network of trachea,
53
tunnels with a pressure gradient where air very slowly can diffuse in and exchange gases with the insect cells.
54
But even insects seem to be able to contract their trachea,
55
and at least some even have specialized breathing organs like spiracles and air sacs.
56
At certain scales, diffusion is just too slow to keep cells alive.
57
The fundamental problem is that the exchange with the environment can only happen at the surface
58
and diffusion of materials can only sustain a certain amount of inside.
59
Tiny living things have only a little bit of inside or volume and a lot of outside or surface area.
60
But what if we wanted to create a bacteria the size of a blue whale and had a very convenient enlargement machine?
61
We would sadly be messed up by the square cube law.
62
In a nutshell, it means that if you make something 10 times larger,
63
its outside or surface would grow by 100,
64
but its insides or volume grows by 1000 times.
65
If we compare the bacterium Pseudomonas aeruginosa with a blue whale,
66
we see that the bacterium has 10 million times more surface in relation to its volume than the whale.
67
The bacterium has a lot of outsides,
68
while the whale has a lot of insides.
69
If we make a bacterium the size of a whale,
70
our giant bacteria now has too much insides,
71
and most of its inside is now very far from its surface.
72
The oxygen our bacterium needs would never reach the inside before it would run out of oxygen.
73
Our giant bacterium would just die.
74
Still, being bigger has many upsides.
75
From making it harder to be eaten to making it easier to eat others.
76
But the size of cells is limited by the distance oxygen
77
and nutrients can effectively diffuse to provide the inside with enough resources.
78
So, life avoided this problem by forming multicellular structures.
79
Beings composed of many cells instead of one.
80
Because diffusion works better if you have many small units instead of one much bigger one.
81
Over time, the cell buddies began to share work and specialize.
82
Some cells concentrated on sensing the environment,
83
others on digestion, others on movement.
84
But that still wasn't enough.
85
The problem of diffusion and surface and energy production remained,
86
limiting the size these first multicellular forms of life could attain.
87
So, in order to become even bigger,
88
life solved the diffusion problem by having holes and caves and tunnels and by folding in on itself,
89
so diffusion could happen easily in each one of the cells.
90
Take yourself.
91
What you consider your outside,
92
your skin, has a surface area of about 2 square meters.
93
But your lungs have a surface area of about 70 square meters.
94
They aren't like balloons.
95
They're more like sponges filled with many tiny packed tiny balloons surrounded by blood vessels.
96
When you breathe in, all these tiny balloons fill up with fresh air.
97
Blood filled up with CO2 is pumped around the balloons.
98
And then the magic of diffusion happens.
99
The oxygen diffuses into the blood where it's picked up by red blood cells.
100
And the CO2 diffuses out of the blood and into your lungs where it can be breathed out again.
101
Your blood then carries oxygen-rich blood into the furthest corners of your body and picks up the CO2 waste.
102
Diffusion in the body is effective at about 1 mm one millimeter
103
so every cell in your body is at most one millimeter away from a blood vessel.
104
So medium-sized animals like you need a lot of blood vessels to reach every cell in the body.
105
Your body has around 100 000 kilometers of capillaries alone,
106
the tiniest of your blood vessels,
107
with a surface area of around 1 000 square meters.
108
This is true for all parts of you that want to exchange something with the outside world.
109
Your body needs surfaces to take in nutrients from your food,
110
so your gut has the surface area of half a badminton court,
111
roughly 40 square meters.
112
The larger you are, the more hidden surfaces you need.
113
Take a tree.
114
Its way to stay alive is to create sugar out of thin air and sunlight.
115
So, it needs as much surface area as possible.
116
An orange tree with 2,000 leaves has a leaf surface area of 200 square meters.
117
But the surface inside the leaves where diffusion actually occurs is 6,000 square meters.
118
The same with roots where water diffuses from the soil into countless tiny hairs that maximize the surface area.
119
The roots of one square meter of grass add up to around 350 square meters of surface.
120
If we look at the breathtaking diversity of life on this planet,
121
it seems like everything is pretty different.
122
And it is.
123
But some basic principles are the same for everybody and have not changed significantly for billions of years.
124
If we look at the very,
125
very small or the very,
126
very big, waste goes out and fresh fuel comes in.
127
Big animals just need a lot of complex plumbing to make it possible.
128
This bird has magical powers.
129
Let's see a demonstration.
130
Bring in the latest scientific research.
131
Wow, that's a lot of complicated stuff about the immune system and all its cells.
132
How could someone possibly understand all of this?
133
Incredible!
134
This overview is delightful and easy to grasp, but still scientifically accurate.
135
Let's make it a bit more difficult.
136
Can she make all of evolution visible at a glance?
137
This is brilliant!
138
You can clearly see the relationships between species and how they evolved.
139
And look at those illustrations!
140
These posters are ready to be shared with the world.
141
These very special pieces of Kurzgesagt are now available on our shop along with many other sciencey products,
142
all researched with care and created with love by the Burbs with magical powers.
143
Every Kurzgesagt product you buy directly funds another moment we get to spend working on our videos.
144
Thank you so much for being a part of our story and for making this channel possible.
145
Thank you.
Scarica l'app
Valutazione AI per ogni frase che pronunci
TRENDING
Popolari
Perché praticare il parlato con questo video?
Praticare la conversazione in inglese attraverso questo video è un modo efficace per migliorare le tue abilità linguistiche. Il video esplora concetti scientifici, il che ti offre un contesto ricco e stimolante per l'apprendimento. Ascoltando attentamente e ripetendo, puoi lavorare sulle intonazioni e sul ritmo della lingua. Il metodo dello shadowing in inglese è particolarmente utile qui; ripetere le frasi immediatamente dopo averle ascoltate ti permetterà di assimilare più facilmente le strutture grammaticali e di migliorare la tua fluidità. Inoltre, puoi cogliere elementi di lessico specifico, rendendo la tua pratica di conversazione in inglese ancora più variata e coinvolgente.
Grammatica & Espressioni nel Contesto
Il video utilizza diverse strutture grammaticali e frasi che possono essere utili nella tua pratica di conversazione. Ecco alcune meritevoli di attenzione:
- "Getting the resources that your cells need": Questa frase evidenzia l'importanza di esprimere necessità e requisiti. Puoi utilizzare questa struttura per parlare di ciò di cui hai bisogno nella vita quotidiana.
- "Doing anything in our universe requires energy": Qui c'è una spiegazione del principio di causa ed effetto, utile per costruire argomentazioni logiche nelle conversazioni.
- "Living things need a lot of different materials": Questa frase offre un buon esempio di utilizzo del plurale e dell'aggettivo per descrivere diversi oggetti e sostanze, arricchendo il tuo vocabolario.
Utilizzando queste strutture, puoi migliorare non solo la tua grammatica ma anche la tua capacità di comunicare idee complesse.
Trappole di Pronuncia Comuni
Il video presenta alcune parole e accenti che potrebbero rivelarsi insidiosi:
- Diffusion: Attenzione alla pronuncia di questa parola, poiché può risultare difficile. Ripetere spesso ti aiuterà a migliorare la pronuncia inglese.
- Molecules: Spesso viene pronunciata in maniera errata; prestare attenzione alla distinzione tra le sillabe potrebbe rivelarsi utile.
Utilizzando metodi di shadowing site, come ripetere immediatamente le frasi, potrai assimilare meglio la corretta pronuncia e fluidità. L'obiettivo è rendere la tua pratica di conversazione in inglese più naturale e meno forzata.
Cos'è la tecnica dello Shadowing?
Shadowing è una tecnica di apprendimento delle lingue supportata da studi scientifici, originariamente sviluppata per la formazione dei traduttori professionisti e resa popolare dal poliglotta Dr. Alexander Arguelles. Il metodo è semplice ma potente: ascolti un audio in inglese di madrelingua e lo ripeti immediatamente ad alta voce — come un'ombra che segue il parlante con un ritardo di solo 1–2 secondi. A differenza dell'ascolto passivo o degli esercizi di grammatica, lo shadowing costringe il tuo cervello e i muscoli della bocca a elaborare e riprodurre simultaneamente i modelli di discorso reale. La ricerca dimostra che migliora significativamente la precisione della pronuncia, l'intonazione, il ritmo, il discorso connesso, la comprensione dell'ascolto e la fluidità del parlato — rendendolo uno dei metodi più efficaci per la preparazione alla prova di speaking dell'IELTS e per la comunicazione reale in inglese.
☕ Offrici un caffè
ShadowingEnglish rimane gratuito al 100% grazie al tuo supporto. I costi del server e IA sono elevati — il tuo caffè ci aiuta ad andare avanti! 🙏