14 votes
Accepted

Is there a significant difference in sedentary calorie-burn between a thinker and non-thinker?

Is there a significant difference in calorie burn? No. The brain, while only making up 2% of our body weight, accounts for ~20% of our energy use at rest. That's because the brain, being critical ...
user avatar
10 votes

How can toddlers expend seemingly boundless energy when they eat so little?

They don't eat little. Consider the volume of milk / food they consume as a ratio of their weight. Quite the contrary they are ravenous machines and their consumption is much higher than an average ...
user avatar
  • 3,675
10 votes
Accepted

Why does caffeine give you so much energy, while being so low on calories?

I agree with @inf3rno: caffeine is a stimulant that acts on the brain and various other parts of the body (Snyder et al., 1981) and I wish to elaborate on its psychopharmacology. Caffeine's effects in ...
user avatar
  • 51.1k
7 votes
Accepted

What causes muscles to generate heat on contraction?

First, it might be helpful to talk briefly about what heat is. It is a form of energy - molecular energy. Basically, heat is the amount of jiggliness of the molecules of a substance or object. When we ...
user avatar
7 votes

How can toddlers expend seemingly boundless energy when they eat so little?

Just to add to the answer from @buzrw: Using data from here and here I have estimated recommended calorie intake per kg for a 2 yr old and for an adult. I've used figures for males and assumed 70 kg ...
user avatar
  • 22.7k
7 votes
Accepted

Organic battery?

I don't have the math at hand for the actually energy efficiency, but let's just start from the storage capacity. Basically, an electric eel wouldn't make a very good battery. They could be a decent, ...
user avatar
  • 36k
7 votes
Accepted

Are there known life forms that are able to transform mechanical energy into chemical energy?

There are no known life forms that use mechanical energy as a primary form of metabolic energy (i.e., for generic cellular functions). Many life forms are sensitive to mechanical disruption in some ...
user avatar
  • 36k
6 votes
Accepted

Breakdown of energy expenditure at the level of a single cell

I was musing on this and did some strange googling, and have some ballpark figures for a bunch of different organisms. It's far from a complete answer but it's at least a start, and all this won't ...
6 votes

Why does caffeine give you so much energy, while being so low on calories?

Caffeine is a stimulant, which helps you release the energy your body stored. Caffeine is a central nervous system and metabolic stimulant,[12] and is used both recreationally and medically to ...
user avatar
  • 4,450
6 votes

Can we harvest energy from plants?

It is not possible to do this directly. Indirectly, it is possible, this is actually done by harvesting fruits - they contain the energy of the sunlight conserved in chemical compounds like sugars or ...
user avatar
  • 49.2k
6 votes

How do plants store energy by potassium battery?

I'll give it a layman's attempt in sort of an "ELI5" approach. I hope the analogy isn't too simplistic, and please don't take it too literally. How do plants use K+? Plants control K+ concentrations ...
user avatar
  • 36k
6 votes

Are there known life forms that are able to transform mechanical energy into chemical energy?

This is definitely not my field, and I have no interest in science fiction, but the question struck me as interesting, and brought me to an area of bimolecular science that may be relevant to the ...
user avatar
  • 22.4k
6 votes

What determines whether a reaction using ATP produces ADP or AMP?

Summary It is the nature of the biochemical reaction that determines whether a reaction of ATP involves hydrolysis of the β- or γ- phosphoanhydride bond. If a part of the ATP molecule is incorporated ...
user avatar
  • 22.4k
5 votes
Accepted

Can we harvest energy from plants?

The most basic example of what I would like to talk about seems to be the algae powered lamp that has (apparently) been developped. I think you misunderstood the idea. That lamp uses ...
user avatar
  • 4,450
5 votes
Accepted

Why do mice have a higher metabolic rate than humans?

In endothermic and ectothermic animals, ie. warm and cold blooded animals, metabolic rates are inversely proportional to size of the organism. Quoting from https://www.biog1445.org/demo/04/...
user avatar
5 votes

Do all prokaryotes have ATP synthases and an electron transport chain?

This is an interesting question (I really mean this — see below), for which a straight answer is remarkably difficult to find on the web. When I googled for it I got pages with statements that ...
user avatar
  • 22.4k
4 votes

What causes muscles to generate heat on contraction?

This is oversimplified, but hopefully clear. When we eat food, metabolic processes break down larger, multi-carbon molecules (like glucose) into smaller molecules. This process is called catabolism, ...
user avatar
  • 3,264
4 votes
Accepted

Burning fat transferred from one part of the body to another

Would the body use this transferred fat for as energy, or would it ignore it as it wasn't stored there in the first place? It would use it as energy source, there is no such thing as "ignored ...
user avatar
  • 4,450
4 votes
Accepted

Is co-transport within a cell active or passive transport?

Co-transport, also called secondary active transport, is a form of active transport because it is using the energy from one concentration gradient to transport another molecule across the membrane ...
user avatar
  • 17.5k
4 votes
Accepted

Does the energy from ATP hydrolysis vary among different cells?

Yes, the energy from ATP hydrolysis can vary between different cell types and condition, because it depends on several factors. Hence, you will find different values in various textbooks. First, like ...
user avatar
  • 5,595
4 votes
Accepted

What are the limiting factors of human stamina?

A few explanations at the cellular and molecular level: First, for contraction to happen, muscles need signals from nerves. Replenishing the pool of neurotransmitters (used for each synaptic burst) ...
user avatar
  • 1,883
3 votes
Accepted

How efficient is the human body at metabolizing food?

A year and a half later, I stumbled upon this article by Ars Technica. To summarize, research/experts acknowledge that the calorie system is a poor way to measure human metabolic performance. Gut ...
user avatar
3 votes

How efficient is the human body at metabolizing food?

I suspect that what you are actually looking for is the following: ...
user avatar
  • 1,402
3 votes
Accepted

NADH shuttles - Why cytosol?

The electrons for shuttling are mainly generated in the cytosol from glycolysis. NADH can easily pass the outer membrane, but must be shuttled over the inner membrane. It is important to consider that ...
user avatar
  • 672
3 votes
Accepted

Does the biosphere have infinite resources and are they infinitely renewable?

No, it is not infinite. The sun has not an infinite mass neither does the earth. So energy is not infinite. But we probably don't really care about that as it applies at a scale we're not really ...
user avatar
  • 67.5k
3 votes

Energy transformations in chemiosmosis and ATP synthase

ATP synthase is basically a pump operating in reverse: while transporters such as the Na/K ATPase uses ATP to push ions against a chemical gradient (resulting in potential energy), ATP synthase uses ...
user avatar
  • 5,595
3 votes

Determining how much energy a plant takes in?

Just a speculation for whether diamond berries could exist or not. This is not an answer for "what is the energy uptake rate of plants" because the actual question tends to be "whether a plant can ...
user avatar
  • 35.1k
3 votes

ATP yield of fermentation: study to cite?

For glycolysis this is really not so much of an issue, because the ATP yield is fixed by stoichiometry. The early biochemistry work by Embden, Meyerhof, Parnas and other that mapped out the reaction ...
user avatar
  • 5,595
3 votes
Accepted

What are the known energy capturing processes in biological systems?

Apart from phototrophy, there is only chemotrophy (obtaining energy from redox reactions of chemical substances) and radiotrophy (obtaining energy from ionizing radiation such as gamma rays). However, ...
user avatar
  • 35.1k

Only top scored, non community-wiki answers of a minimum length are eligible