How does a banana know how to grow? Does it have a brain? Can it think?

Question

How does a banana know how to grow? Does it have a brain? Can it think?

Answer 1

Some interesting answers here.  For a start a banana does not have what could be termed a brain.  It is also not considered to be concious so with that under consideration it could be argued that it does not think either.  

Your question is interesting though.  Why does a banana indeed grow?  Why do banana plants grow to a certain size before producing fruit and how does that fruit 'know' when it has grown big enough.

The answer ultimately lies in the DNA, as a number of people have mentioned before.  Again though, the DNA does not 'think' on behalf of the banana, it merely codes for certain molecules called proteins that allow the banana plant to respond to different environmental conditions and hopefully grow successfully.  Proteins are often described as the 'building blocks' of life but their use also extends to cell receptors and chemical feedback transmitters.  

The regulation of growth is essentially a massive web of negative feed back mechanisms revolving around the proteins which the DNA codes for.  When a small banana plant begins to grow it's efforts will be concentrated around rapid photosynthesis and growth.  Good sunlight, temperature, water supply and soil nutrients will all stimulate the plant to photosynthesise and use the energy from this to grow.  Cut off any of these factors and the plant will feedback this information to itself via chemical feedback mechanisms and cease the growth accordingly so it can save it's energy and resources for a time when growing conditions are more favourable again.  

Interestingly most plants (the banana being no exception) will grow towards light sources.  This is an excellent example of how hormonal feedback mechanisms can affect growth and make the plant appear to 'think'.  What is actually happening is light receptors (proteins) produce more of a specific hormone (auxins I believe) which then stimulates growth more in one area of the plant that another and hence the plant grows more towards the light.

Another example I can state is if the plant is grazed on by an animal.  The growing tips normally send back hormonal messengers that inhibit growth in the rest of the plant, one of the reasons they grow upwards.  If that tip is bitten off or damaged sufficiently then the hormones cease to be made and growth continues elsewhere, usually at the next suitable point down on the branch or stem.  

Fruit growth is perhaps more complicated but essentially using the same framework.  Once the plant reaches a certain size and conditions are favourable (some plants have receptors that sense the length of day and hence the time of year) feedback will trigger certain hormonal changes that will stimulate the plant to produce flowers (the proteins, like most things, for this of course coded for by the DNA) once these flowers are pollinated successfully and conditions are adequate, fruit growth will be stimulated.  The eventual size and characteristics of the fruit are again stimulated by feedback mechanisms similar to those used in the initial growth described above.  The plant can regulate how much resource it can put into growing the fruit.  Different DNA in different banana plants of course affects how it will build the banana and respond to changing conditions.  This is why you get different types of bananas and even those of the same type may not appear very similar becuase they were grown under different conditions.  

Growth (and repair) in your own human body is essentially also contributed by the same mechanisms, hence the other answer stating that you don't 'think' in order to grow. In commercial cases the hormonal effects can be exploited by clever growers.  For example they will take cuttings from plants and then dip the ends in rooting hormone in order to stimulate root growth so they can establish a nursery of new plants quickly.  

I hope that helps explain it at a high level.  It would be very difficult and long winded to explain every single step, DNA to protein and so on, so I've tried to talk about it in more general terms with examples.  

Answer 2

The DNA in banana's cells tells it how to grow.

Answer 3

no it cant think silly of course not

Answer 4

Did you know how to grow ? Do you think you grew "because" you knew how exactly you should grow..? No. You just grew up. Right. 'Thought' or 'Intelligence' isn't everything. It's just a characteristic of the human mind.

Answer 5

I will like to know what is in your brain to have the courage of asking something like this. LOL

Answer 6

You sound a bit bananas yourself.

Answer 7

The cells in a seed have a nucleus and its DNA will split and copy its self then the cells split to make two cells, this continues until you have a bannana. Basicaly its dna acts as a checklist to tell its cells what to do, so in a way a bannana does have a brain, but it cant think really

Answer 8

Chemistry I think,cause and effect.

Answer 9

You don't have to think to grow.  It happens to people without them causing it, doesn't it?

Answer 10

no it doesn't have a brain or it cant think i think that it just goes towards the sun