Poshpaws
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Is there a reason why human eyesight and plants make use of the same wavelength of light?
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103 votes

Good question. If you look at the spectral energy distribution in the accepted answer here, we see that photons with wavelengths less than ~300 nm are absorbed by species such as ozone. Much beyond ...

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Life without DNA?
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39 votes

To follow up what mbq said, there have been a number of "origin of life" studies which suggest that RNA was a precursor to DNA, the so-called "RNA world" (1). Since RNA can carry out both roles which ...

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What is the lowest pressure at which plants can survive?
22 votes

I like your question! Low surface pressure on Mars (averaging 600 Pa or about 1/170 of Earth's at sea level) is only one difficulty that an organism would have to contend with. In addition, mean ...

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Why do plants have green leaves and not red?
22 votes

There is quite a fun article here which discusses the colours of hypothetical plants on planets around other stars. Stars are classified by their spectral type which is dictated by their surface ...

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Are single-celled organisms capable of learning?
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19 votes

I'd like to know what is the reference for amoebic learning. I cannot comment directly on this, but there is some evidence for "adaptive anticipation" in both prokaryotes and single-celled Eukaryotes ...

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When did vision evolve for the first time?
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14 votes

I'll address the question in the title "At which time did sight evolve for the first time?" by assuming that by the evolution of vision, we mean the evolution of the eye. Molluscs are an excellent ...

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How do fairy rings propagate?
13 votes

In addition, the mycelia (the underground mass of hyphae which constitutes the bulk of the fungus) expand outwards because they decompose organic matter in soil as they go, leaving very little organic ...

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How do biological communities at deep-ocean hydrothermal vents migrate between vents?
12 votes

Following up on Alexander's response, I read a little more on the subject by looking at some of the references in the Johnson et al. paper. This paper discusses an interesting case where researchers ...

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Why do some plant species have lobed leaves, while similar species in the same habitat don't?
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11 votes

This is a question for which, I think at the moment, we don't have a clear answer. It is important to bear in mind that the leaf plays a number of important roles in the plant (photosynthesis, ...

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Free Radicals for aging
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10 votes

Free radicals are damaging because their unpaired electrons (or not fully filled valence shell) makes them highly reactive species. They are often considered together with highly oxidizing "reactive ...

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Human perception of time depending on age
10 votes

There may be some clues in neurobiology. A possibility may be that a person's general emotional state may affect their perception of the passage of time, as argued in this article and references ...

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How would a plant sprout and grow in a zero gravity environment?
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10 votes

There have been several experiments in growing plants in microgravity (strictly speaking, we do not achieve "zero-g" since astronauts remain in orbit about the Earth). Changes in plant growth due to ...

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How did the first self replicating organism come into existence?
9 votes

We don't know how self-replicating molecules first arose (and probably never will know exactly) but the Earth is large and had 500 million years (i.e. the prebiotic Earth timescale) or so to ...

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Is there life on other planets and if so how frequent?
8 votes

OK, so we know a couple of things about life in the universe. Note, however, that this is not really an answer and is also not very biological in nature. So, we don't know how life began on the Earth....

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Are there any plants that fix their own nitrogen?
8 votes

As far as I know, all biotic nitrogen fixation is performed by prokaryotic organisms such as Rhizobium. I don't know of any plants which can carry out this function on their own. Plants can't use ...

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Why do plants have pith and how is it useful to them?
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8 votes

The pith (medulla) forms part of the ground tissue system of a plant, and specifically it is the ground tissue which lies interior to a plants vascular tissues (xylem, phloem etc.) The ground tissue ...

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Defining paper(s) in epigenetics
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8 votes

I understand that Robin Holliday was the first to discuss the possible role of DNA methylation in the control of Gene expression. In his paper "The inheritance of epigenetic defects" he presents what ...

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What is the most difficult feature to explain evolutionarily?
7 votes

The Nautilus eye used to be (still is?) a "problem" and became a poster boy for creationist arguments. It has a pin-hole camera eye, which is the highest resolution non-lens eye. However, I ...

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What elements are a possible basis for life?
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6 votes

This is an interesting question, particularly considered in the context that Cairns-Smith (1985) even suggested that clays (silicates in solution) may have had some sort of early selection acting on ...

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Why can you graft two unrelated cacti successfully, but you cannot do this on garden trees?
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6 votes

Firstly, different genera of trees can occasionally be successfully grafted. For example, quince, genus Cydonia, may be used as a dwarfing rootstock for pear, genus Pyrus. However, it is true to say ...

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How did the nucleobases in the Murchison meteorite form?
5 votes

I think it's fair to say that we don't really know how these more complex organic molecules formed abiotically, but we can say that carbonaceous chondrites - a class of carbon and organic molecule ...

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Should we be looking for extra-terrestrial life on comets?
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4 votes

Yes we should be and we are! Scientists have been analysing cometary material - but its a challenging task. The problem with looking at meteoritic material from comets on Earth is that it is generally ...

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How does the NAD+/NADH ratio affect lifespan in vertebrates?
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4 votes

This study found a statistically significant decline in NAD+:NADH ratios and in intracellular NAD+ with age in the organs of rats. They discuss that the activation of PARP - the NAD-dependent ...

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Why do cucurbits produce so much fluid when their stems are cut?
4 votes

Looking through some papers it is not clear to me that botanists actually know why this should be the case, and I am sure that you are more qualified than me to comment on this Richard! However, there'...

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What would need to be discovered to prove there is extraterrestrial life?
3 votes

In the simplest sense, extraterrestrial life is life found beyond the Earth. Defining what life itself is notoriously difficult - perhaps the best is a system which is subject to Darwinian evolution? ...

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How are there multiple varieties of the potato?
2 votes

Well, uvesten is correct in saying that potatoes are flowering plants and as such they can reproduce sexually. However, as everyone mentions potatoes can, like many plants, reproduce asexually by ...

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