Why only some plant cuttings grow when put in water?

Why only some plant cuttings grow when put in water?
Does a second dose of vaccine restart immunity or does it carry the 80% protection from the first dose through the whole process?
How do T cells recognize the S protein as an antigen on MHC-1 for the mRNA covid vaccine if it is foreign?
Where does the mass go when not conserved in chemical reactions?
Why don't we see any main sequence Red Giants or Blue Dwarfs?
How did moderna finally determine a safe and effective dose of lipid nanoparticles to use in the COVID vaccine?
Why don't the tides bring the moon closer to the Earth?
What causes a metallic taste after Pfizer’s COVID-19 vaccination?
For Covid survivors, is further and frequent exposure to virus boosting immunity or increasing the risk of re-infection?
How do you get different elemental properties from slight variations in the amount of electrons orbiting an atomic nucleus?
We often hear that the majority of the ocean is unexplored. Are we trying to change that and if so, what are we exploring and finding?
Why did Horizons only fly by Pluto?
How does your immune system recognise a foreign organ (after organ transplant) ?

Posted: 15 Apr 2021 11:05 PM PDT

There are some plants that will happily grow roots and be perfectly happy when put in just water, like some vines. Put just a bare section from a willow tree in a jar of water and it will grow roots and a new shoot of leaves from the top. But a branch taken from a birch will first grow leaves but then start to wilt within a week.

Why don't all plants or trees be like willows?

submitted by /u/purplecow
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Does a second dose of vaccine restart immunity or does it carry the 80% protection from the first dose through the whole process?

Posted: 15 Apr 2021 06:25 PM PDT

Will you still be 80% protected from the first dose immediately, or a day or two, after receiving the second, or are you back to no immunity until the second dose is fully active?

submitted by /u/hippopotma_gandhi
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How do T cells recognize the S protein as an antigen on MHC-1 for the mRNA covid vaccine if it is foreign?

Posted: 15 Apr 2021 11:06 PM PDT

I've scoured the internet to find this, and a lot of answers are along the lines of "yeah your body just know that the S protein = bad when presented on MHC-1." As you can expect, this isn't very informative.

From my understanding, the mRNA vaccine doesn't secrete the S protein extracellularly either, so they aren't phagocytized by an antigen-presenting cell.

I was thinking maybe there's a specific T cell that binds to MHC-1 and somehow has a receptor for that S protein? Is this the case? Because there is a huge variation of T-cells made with different receptors right?

If this is the case, isn't it quite ineffective to wait for a T-cell to come along with maybe a 1 in a million chance of having a receptor that binds to the S protein (Covid spike protein)?
Is there another way that our body recognizes the S protein as an antigen?

submitted by /u/PythonHammer
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Where does the mass go when not conserved in chemical reactions?

Posted: 16 Apr 2021 05:37 AM PDT

I have read that mass changes in chemical reactions, for example through making and breaking bonds, but it is too small to detect. In balanced equations for non-nuclear reactions, there are the same number of protons, neutrons and electrons on both sides. If the equation is balanced, where is the mass change? Do the electrons/neutrons/protons slightly change their mass, or is the mass change hidden somewhere else?

submitted by /u/AmazingMeltedSnowman
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Why don't we see any main sequence Red Giants or Blue Dwarfs?

Posted: 15 Apr 2021 11:54 PM PDT

Pretty simple question, probably with a pretty simple answer. Blue Dwarfs are a theoretical stage of life for Red Dwarfs, that much I know, but why don't we see any small main sequence Blue stars? Is it just not possible to get that hot and that small? And the same goes for Red Giants - all the big stars seem to be Blue. Why are none of them Red? Why is that only the dying stage of a larger star?

submitted by /u/MonsieurToast
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How did moderna finally determine a safe and effective dose of lipid nanoparticles to use in the COVID vaccine?

Posted: 15 Apr 2021 08:05 PM PDT

In 2017 moderna shelved it's mRNA technology because they couldn't get the therapy to work. All due to the toxicity of lipid nanoparticles. The structure that carries the synthetic mRNA to cells(?).

What changes were made in less than three years that made the delivery of COVID mRNA safe?

submitted by /u/sevensixer
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Why don't the tides bring the moon closer to the Earth?

Posted: 16 Apr 2021 01:01 AM PDT

Here I have linked a diagram. https://i.imgur.com/FHdbSjj.jpg

I understand how the friction from the earth spinning against the water causes the ocean bulge to drift ahead of the moon.

However, I do not understand how that bulge causes the moon to drift AWAY from the earth.

If I draw a line between the bulge and the moon, wouldn't an attraction along that line bring the moon closer to the bulge? (and subsequently closer to the earth?)

Thanks.

submitted by /u/SalvosMachina
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What causes a metallic taste after Pfizer’s COVID-19 vaccination?

Posted: 15 Apr 2021 07:18 PM PDT

Some patients report having a strange, persistent metallic taste after being vaccinated with Pfizer's mRNA vaccine.

This has been reported by news outlets as a "phenomenon". For example, NBC News: https://www.nbcnews.com/news/amp/ncna1261944.

I was wondering if any biologists, doctors, etc. could provide a biological explanation for this side effect.

Disclaimer: I received Pfizer myself today, and I experienced this rare effect. This post is not meant to deter vaccination in anyone. It just seemed like a good question.

submitted by /u/cajundev25
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For Covid survivors, is further and frequent exposure to virus boosting immunity or increasing the risk of re-infection?

Posted: 15 Apr 2021 05:10 PM PDT

As in the title. That's a question about any similar disease really. If someone has acquired immunity through infection, and afterwards frequently comes into contact with carriers, does that boost their immunity (because there's "reminder" for the immune system of what to fight with) or does that increase risk of re-infection (because of prolonged exposure and concentration of viruses)?

submitted by /u/TeoTN
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How do you get different elemental properties from slight variations in the amount of electrons orbiting an atomic nucleus?

Posted: 15 Apr 2021 11:52 AM PDT

I never intuitively understood how you go from atoms to the actual elements, with all of their specific properties. How can the amounts of electrons in an atom determine the color, shape, conductivity, fluidity, etc. of an element?

submitted by /u/benisbrother
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We often hear that the majority of the ocean is unexplored. Are we trying to change that and if so, what are we exploring and finding?

Posted: 15 Apr 2021 01:24 PM PDT

As the title says. I've often heard that we know more about the moon than we do our own ocean. Are we actively trying to change that and if so, what are some of the exciting projects ongoing which are giving us some new insights in the oceans.

submitted by /u/jimguru
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Why did Horizons only fly by Pluto?

Posted: 15 Apr 2021 04:41 PM PDT

Why did the engineers decide to only fly by Pluto, when it would seem more science could be collected by placing it in an orbit?

submitted by /u/Could_0f
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How does your immune system recognise a foreign organ (after organ transplant) ?

Posted: 15 Apr 2021 08:05 AM PDT

submitted by /u/lifesaboxofchoco
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