Most Popular
1500 questions
13
votes
2 answers
Can "red" cone cells actually see much red light?
In electronics, the most common color scheme is the "red-green-blue" (RGB) scheme. This choice is often justified by claiming that the long- (L), medium- (M), and short- (S) type cones in the human eye are most sensitive to red, green, and blue…
tparker
- 717
- 5
- 20
13
votes
4 answers
Why do human females have permanently prominent breasts?
Humans seem to be the only animal whose females have breasts that permanently have a "full" appearance, ie a prominent amount of tissue even when not lactating, whereas other species' breasts seem to almost totally "deflate" when not longer…
Bohemian
- 683
- 2
- 6
- 13
13
votes
3 answers
How does sodium in one's diet affect blood pressure?
Due to high blood pressure, my doctor has recommended I go on a low-sodium diet. So, that got me wondering what it is about sodium that drives this recommendation?
What does sodium do to a body that, by its presence or absence, affects blood…
Iszi
- 231
- 1
- 2
- 9
13
votes
1 answer
Help to identify this large, slow-growing mushroom?
Here in my backyard in Southern California, there appears to be this relatively smooth, mottled-colored dome-like structure a little larger than a chicken egg in the dirt. Can anyone identify it? Is it some sort of insect nest or a multicellular…
A L
- 939
- 8
- 20
13
votes
2 answers
Is there any evidence that a virus can modify human evolution
I was just reading Evolution of lactose tolerance, and in it one line says "But there was a time in human history when our diet and environment conspired to create conditions that mimicked those of a disease epidemic".
Something I've always…
daven11
- 233
- 1
- 5
13
votes
2 answers
What spider is this? Is it dangerous to humans?
What is the species? Is it dangerous to humans?
I chanced upon this beautiful one near our water well. It stood at a height where an adult could accidentally walk through the web and the spider would land on one's face.
As a test, I dropped a piece…
NVZ
- 243
- 5
- 12
13
votes
1 answer
Are these spider eggs?
I was pulling weeds in my backyard in Southern California, when I saw a spider over a white area on the underside of one of the leaves. It's staying right near the white spot. Are those spider eggs? Also, what kind of spider is this?
A L
- 939
- 8
- 20
13
votes
3 answers
How does the brain immediately know when one's thirst has been quenched?
The question struck me the other day when I drank a glass of water. I understand that there are at least two conditions under which the brain signals thirst: extracellular thirst, when there's not enough fluid in the blood, and intracellular thirst,…
Jonathan Quinth
- 133
- 6
13
votes
1 answer
What species of fox is this?
I found this picture of a fox in a news article about arctic foxes in Sweden (source), but I'm not sure whether it is actually an arctic fox.
On the one hand, it has white fur, which is the correct winter coat for an arctic fox. On the other hand,…
Gwen
- 883
- 6
- 27
13
votes
4 answers
Can viruses be toxic?
Bacteria can produce toxins like endotoxins and exotoxins. In diseases like cholera or tetanus they can harm infected people due to these toxins.
Now, although viruses are much smaller and are dependent on the host cell for their production, are…
Marijn
- 2,765
- 1
- 20
- 35
13
votes
1 answer
Why is DNA double stranded and RNA single stranded?
Why is DNA present as a double helix structure and RNA as a single helix? What causes the difference between them? What are the practical physiological differences between dsDNA and ssRNA? How are the key biophysicochemical features responsible for…
Abdul Satar Aswed
- 131
- 1
- 1
- 5
13
votes
3 answers
50:50 sugar/fat mixture
A couple of years ago I saw a BBC Horizon television documentary about sugar and fat. One section mentioned three experiments in which rats were given their ordinary rat food plus and unlimited supply of:
Experiment A. Unlimited sugar
Experiment B.…
Mick
- 199
- 1
- 14
13
votes
2 answers
Protein tertiary Structure formation
As we know that coils and loops are evolutionary variable regions where mutations,deletions, and insertions frequently occur. So does it mean that they don't have much role in the structure of protein? If it so then what are the factors for the…
katherinebridges
- 1,195
- 3
- 11
- 27
13
votes
1 answer
Why is ATP produced in photosynthesis used to synthesize glucose?
In photosynthesis ATP is produced in light-dependent reactions only to go to the Calvin cycle to be turned into glucose to make ATP during respiration:
Why isn't this ATP just directly released into the cell? Is there a benefit to using the ATP to…
tox123
- 508
- 1
- 4
- 20
13
votes
1 answer
Do any animals prepare food?
I was just wondering if any animals (are smart enough to) enhance the flavor of their food by, for example, mixing ingredients or seasoning or letting it cure in some ways. In the first episode of Life (on Netflix), they show a monkey who dries some…
amphibient
- 329
- 2
- 6