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Top new questions this week:

Why are HeLa tumors purple?

I remember hearing that the tumor where HeLa cells originated from was purple and jelly like, and I've seen pictures from studies with rats and HeLa tumors, and their tumors appear to also be purple. ...

asked by magpie58 5 votes
answered by TheChymera 6 votes

Is there a definition of species where Lions and Tigers are the same species?

According to Species concepts There are at least 26 recognized species concepts And according to Why are lions and tigers considered different species (not sure how reliable this source is ...

asked by Pablo 3 votes
answered by JackalFrost 4 votes

How does coffee cause calcium loss in our body?

Recently on radio a doctor advices to reduce the consumption of coffee as it leads to calcium loss(as my mother described). My initial response was: How could such thing be possible? What kind of ...

human-biology metabolism bone-biology calcium  
asked by Ramanujan_π 3 votes
answered by Jan 2 votes

Can a bacterium express a virulence gene and not produce toxins and what may be the cause of this?

I am preparing a seminar on viable but non-culturable (VBNC) state in bacteria, mainly foodborne pathogens and I just saw this line in a journal article by Lothigius et al that "the expression of the ...

microbiology gene-expression virology  
asked by Mohammed 3 votes
answered by Mohamed 0 votes

What is the effect of self envenomation on reptiles?

If a venomous lizard bites its own tongue will it die? I've searched the whole internet and I am unable to find a reliable answer on self envenomation.

zoology homework poison  
asked by Karam 2 votes
answered by Frieke 2 votes

How to model species interactions on population size dynamic?

Here are two classical discrete time models of population size dynamic. The exponential growth model $$N_{t+1} = r\cdot N_t \qquad\qquad(1)$$ and the logistic growth model $$N_{t+1} = r\cdot N_t ...

ecology theoretical-biology population-dynamics population-biology  
asked by Remi.b 2 votes
answered by Cheesebread 1 vote

Analysis of post transplantation lineage tags

I'm having some trouble understanding some bits of a study, mostly about the Sleeping Beauty system and TARIS model, from this paper: I ...

genetics molecular-biology  
asked by tw1 1 vote

Greatest hits from previous weeks:

No. of meiotic divisions to produce specific no. of seeds

If I want to produce 100 seeds. Then the no. of meiotic divisions is 125 which can be calculated by the formula x + x / 4. x = no. of seeds produced. How is this formula derived?

meiosis sexual-reproduction  
asked by RuBisCO 4 votes
answered by user237650 7 votes

How can a drink contain 1.8 kcal energy while 0 g fat/carbs/protein?

How is it possible that the Red Bull Zero contains 0 gramms of fat, carbs and protein, but it still has 1.8 kcal of "energy". I always thought that the human body can gain energy only from 3 kinds of ...

food nutrition food-chemistry  
asked by Crouching Kitten 23 votes
answered by Jan 26 votes

Which human cells have the longest and shortest lifespan?

Which cells in a human have the longest lifespan? Which cell has the shortest lifespan?

human-biology cell-biology  
asked by S.Sunil 14 votes
answered by PlaysDice 10 votes

Is a butterfly one or two animals?

I have read somewhere that a butterfly might be two animals that combined together. One animal was a worm-like creature and the other an insect. And the insect basically hatched inside the worm. ...

asked by zooby 39 votes
answered by Karl Kjer 102 votes

What is the cause of muscle cramps?

According to Wikipedia, muscle cramps are caused by the inability of myosin fibers to break free from the actin filaments during contraction, resulting in a prolonged contraction. A lack of ATP would ...

physiology muscles  
asked by Kenshin 12 votes
answered by mikedugan 7 votes

How long can human tissue last without blood?

I've heard it said various times that the body's tissues will begin to necrotize after being cut off from the blood supply for only a few minutes, but that can't be true. A few years ago, I woke up ...

asked by Mason Wheeler 11 votes
answered by L.B. 14 votes

What happens to the holes in the skull where teeth were developing?

In Skeptics.SE, a question regarding the skulls of children arose. Depicting a scary skull where the permenent teeth are "hidden" inside the jaws and the milk teeth are in the their place. After all ...

human-biology teeth  
asked by SIMEL 6 votes
answered by mikedugan 6 votes

Can you answer these questions?

Environmental Carrying capacity concept

In many textbooks the carrying capacity is defined mathematically as the intrinsic growth rate divided by the intraspecific coefficient $K_{i}=\frac{r_{i}}{\sigma_{ii}}$. If I have for species ...

asked by F.O 1 vote

Calculate Q10 using the best line of fit

The question: The equation of the line of best fit is y = 3.5097x+16.529 I do not understand how to find the Q10 by solving the best line of fit. The observed data:

asked by mk2025 1 vote

Which birds are capable of flying both forward and backwards?

Very random question - but it's often said that the hummingbird is the only bird that can fly backwards (for example, ...

zoology ornithology  
asked by Adrián Moreno 1 vote
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