39 votes

Is the amount of the soil reduced when plants grow?

The vast majority of the mass of a plant is carbon-based which is obtained directly from the air via photosynthesis. So trees are, in a loose sense, solidified air! And most of the mass that comes ...
lemon's user avatar
  • 451
37 votes

Why don't viruses reach broad concentration outdoors in a city like allergens?

2, 4, 5, and 6. 6 being that the UV light (from the sun), fluctuations in temperature, humidity, wind etc mean that the virions are decayed relatively rapidly for most virus species. To address (1): ...
bob1's user avatar
  • 12.1k
33 votes

Can bacteria be killed by purely physical trauma?

My (limited) understanding is that it is quite hard to avoid killing some bacteria even with very gentle physical manipulation. On the other hand, it is quite hard to use physical force to achieve ...
Martin Modrák's user avatar
32 votes
Accepted

Why don't membrane proteins move?

Proteins can move around the membrane. Most proteins do move within the membrane. The membrane is a liquid crystal and has fluid behaviour. Specifically, this is due to the membrane being in a gel-...
James's user avatar
  • 11.3k
28 votes
Accepted

Why is saltatory conduction in myelinated axons faster than continuous conduction in unmyelinated axons?

Short Answer Myelination acts as an electrical insulator and allows saltatory propagation. By reducing membrane capacitance and increasing membrane resistance, myelination increases the velocity of ...
theforestecologist's user avatar
24 votes
Accepted

Can UV radiation be safe for the skin?

You're talking about long-wave UV, or UV-A radiation. In the 80s, experts claimed that this was a safe wavelength. Protection against UV-A was not part of sunscreen in the early days. Consequently, UV-...
S Pr's user avatar
  • 6,222
22 votes

Why don't viruses reach broad concentration outdoors in a city like allergens?

In another answer elsewhere on StackExchange, a poster estimated that there might be something like 100 g to 1 kg of SARS-CoV-2 virus worldwide, and that's an estimate of all the virus, including what ...
Bryan Krause's user avatar
  • 45.7k
21 votes
Accepted

What is the anatomical term for a two jointed leg?

Welcome to Biology.SE! I think you are talking about plantigrade, digitigrade and unguligrade. Please note that the number of joints in mammals does NOT vary, but only the relative length (and shape)...
Remi.b's user avatar
  • 68.1k
21 votes

Can bacteria be killed by purely physical trauma?

There are plenty of physical or mechanical methods of killing bacteria, but most are used in conjunction with other agents and probably don't qualify as "blunt force trauma". For example, ...
MikeyC's user avatar
  • 4,724
17 votes

Why does UV radiation from the Sun cause skin cancer?

Rather than 'breaks' caused by high energy radiation, UV radiation causes chemical modifications of the bases ('letters') that make up DNA. There are four bases in the DNA alphabet abbreviated to A,T,...
mimat's user avatar
  • 1,425
16 votes
Accepted

What physical evidence exists that shows motor proteins "walking" within a cell?

Since you chose kinesins as an example class of motor proteins, I will also stick to them. In general, the movement mechanisms of kinesins are well studied and the general structure of kinesin ...
AlexDeLarge's user avatar
  • 2,868
15 votes

Why does UV radiation from the Sun cause skin cancer?

There are very many photochemical reactions: Up to 50–100 mutagenic reactions on DNA per second might occur in a skin cell during exposure to sunlight, but are usually corrected within seconds by ...
bandybabboon's user avatar
  • 10.4k
9 votes
Accepted

How much energy does a small spider expend per day just waiting for its web to vibrate?

Short answer Approximately 240 J on a daily basis. Background Ballesteros et al. (2018) modeled basal metabolic rates of insects. They reckoned that endotherms, like insects, basically use energy ...
AliceD's user avatar
  • 52.4k
8 votes
Accepted

Would the human body react faster to touch or sight

A "touch" or "haptic" sensation will be much faster due to several reasons: Haptic feedback can be processed without the presence of any higher-order cognitive processing, therefore meaning that the ...
Ebbinghaus's user avatar
  • 2,603
8 votes
Accepted

What is the biological potential for vision of wavelengths outside the human visual range?

There are some limits on what light can be detected biologically based on physics and chemistry. Although there are animals that can sense more UV or more infrared than humans, they are still subject ...
Bryan Krause's user avatar
  • 45.7k
8 votes

Can any organisms see non-electromagnetic radiation?

Some fungi have radiotropism; they grow toward radiation sources. Melanin-expressing (melanotic) fungi migrate toward radioactive sources, which enhance their growth. According to this paper. These ...
BPinto's user avatar
  • 478
8 votes
Accepted

Should there be separate Ramachandran plots for an amino acid in different contexts?

The phi and psi dihedrals describe the dihedral on both sides of the c-alpha of a single amino acid, and do not involve any angles of the neighboring amino acid. The Ramachandran plot is something ...
VonBeche's user avatar
  • 1,473
7 votes

Why don't membrane proteins move?

No other answer has mentioned this so I created an account just to say this. Some membrane proteins do not move. This is because they are fixed in that position in the membrane due to the ...
Vampiric Scum's user avatar
7 votes
Accepted

Is Einstein's mass energy equivalence ($E=mc^2$) relevant to biological systems?

Short answer Any law of physics will of course be applicable to living beings. However, in the absence of mass gain and mass loss, the input = output equation for ...
Remi.b's user avatar
  • 68.1k
7 votes

Is the amount of the soil reduced when plants grow?

The soil is the source of a small quantity of vital elements like magnesium (component of the chlorophyll), phosphorus (DNA), sulphur (some proteins) and more. As the plant grows, these are removed ...
Martín-Blas Pérez Pinilla's user avatar
7 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 ...
David's user avatar
  • 25.7k
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 ...
Bryan Krause's user avatar
  • 45.7k
7 votes
Accepted

Difference between prions and amyloid proteins?

Amyloids are protease resistant insoluble fibrils formed because of (mis)folding and aggregation of soluble proteins (Rambaran and Serpell, 2008, Sabate et al., 2015). The first definition of prion ...
WYSIWYG's user avatar
  • 35.6k
7 votes

Can UV radiation be safe for the skin?

There are (at least) two sides to this story. One is direct DNA damage being caused by UV-B light which happens to have photons with just the right amount of energy to interact with thymine. This has ...
Damon's user avatar
  • 259
6 votes

How's the membrane potential restored to resting state after hyper polarisation?

The Na,K-ATPase restores negative membrane potentials. When a cell is hyperpolarized, leaky K+ channels take care of that. Leaky K+ channels are always open. Generally, K+ has the tendency to diffuse ...
AliceD's user avatar
  • 52.4k
6 votes

Is Einstein's mass energy equivalence ($E=mc^2$) relevant to biological systems?

No, the mass-energy convertibility has no practical relevance to biology. The amount of mass produced or lost in the chemical reactions in biological systems is so small as to be immeasurable and is ...
mgkrebbs's user avatar
  • 9,054
6 votes

Why don't membrane proteins move?

There are two types of proteins that are present in a membrane, because you have not been specific about which type of protein you are talking about I will consider that you are talking about Integral ...
Harsimran kaur's user avatar
6 votes
Accepted

What is meant with “the chest wall and lungs are coupled together”?

How are the lung and chest wall coupled? You have your answer in the text: the surface tension between the lungs and the chest wall And as you say, it is very much like there is a physical-...
De Novo's user avatar
  • 8,791
6 votes
Accepted

Do electric eels produce current as they just move about, and how/why?

You are right - the 800 Watts are not constantly produced: There are three types of electrical discharge: (i) low voltage (ii) high voltage doublets or triplets and (iii) high voltage high frequency. (...
dtadres's user avatar
  • 666
6 votes

How do physics notions of fluid dynamics relate to pressure gradients in circulation?

As far as we know so far, biology isn't able to break any laws of physics. However, biology isn't passive: biological systems react to changing environments to maintain some level of homeostasis. ...
Bryan Krause's user avatar
  • 45.7k

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