Jump to content
Search In
  • More options...
Find results that contain...
Find results in...
Sign in to follow this  
suap

Why do onion cells have no green dots (chloroplasts) in them?

Recommended Posts

so ive been on the internet looking for the answer but got nothing

can any of u smart people on here help out?

Share this post


Link to post
Share on other sites
This forum is brought to you by the 12ozProphet Shop.
This forum is brought to you by the 12ozProphet Shop.
This forum is brought to you by the 12oz Shop.
Guest imported_El Mamerro

Do they need them? They don't receive any sunlight underground...

Share this post


Link to post
Share on other sites

CHLOROPLASTS IN ONION ROOT CELLS

 

http://images.encarta.msn.com/xrefmedia/sharemed/targets/images/pho/t013/T013558A.jpg'>

 

Chloroplasts are minute, green, spherical structures that are essential to the process of photosynthesis. The chlorophyll molecule, a very complex organic molecule composed primarily of magnesium, carbon, and hydrogen, regulates the absorption of the red, violet, and blue portions of the visible light spectrum.

 

Mammero hit the nail on the cudicle:

 

No, this has nothing to do with dead cells. In truth the practical answer

to this is that they don't need chloroplasts. Think of where an onion

lives and how much light it normally receives. Chloroplasts only function

in the presence of light. Because it costs energy to develop chloroplasts,

it is not useful for the plant to put develop them if they won't function.

However accurate, this answer is a little simplified compared to what

really happens.

 

Chloroplasts are only one type of plastid, along with chromoplasts (causing

the red color of peppers and tomatoes) and amyloplasts (storing starch in

potatoes and corn). None of these plastids can be assembled from raw

materials within the cell of a plant. Rather they all develop from another

type of plastid called a proplastid. Proplastids are small and clear.

They divide at the same time the cells divide, so every cell in a plant has

proplastids. However, they are difficult to see in most plants because of

their size.

 

One piece of evidence that the proplastids exist in onion cells is easily

seen. Leave an onion exposed to light for several days or weeks. It will

begin to grow new green leaves. Also, some of the outer layers of the bulb

(actually leaves, too), will begin to green up, as their proplastids

develop into chloroplasts.

 

According to Eames and MacDaniels (1925, p 12)

Plastids may be found in all living cells of a plant, and probably are

present in every cell in the early stages of development. Later they

become restricted to certain cells, and are abundant only in those which

have specialized functions, such as photosynthesis, storage, and color

manifestation. Plastids do not occur in the fungia, bacteria, …

…Plastids multiply freely by division, and in this way the large numbers

present in some cells are in part secured. Plastids are present in the

very young meristematic dells where they are very minute, the smallest

being at the limit of [light, not electron] microscopic visibility.

 

References:

 

Eames, A.J. and L.H.MacDaniels. 1925. An Introduction to Plant Anatomy.

McGraw-Hill Book Company, Inc:NY.

 

Esau, K. 1953. Plant Anatomy. John Wiley And Sons, Inc:NY.

 

Esau, K. 1977. Anatomy of Seed Plants, 2nd ed. John Wiley and Sons,

Inc:NY.

Share this post


Link to post
Share on other sites

i just need a 1 sentance answer for a take home test

 

how can i simplfy itt 26cube?

 

 

thanks for the help

Share this post


Link to post
Share on other sites
Originally posted by GnomeToys

They're root cells. Onions grow their leaves above ground, and have their chloroplasts there.

Share this post


Link to post
Share on other sites
Guest imported_Tesseract
Originally posted by suap

i just need a 1 sentance answer for a take home test

 

how can i simplfy itt 26cube?

 

 

thanks for the help

 

you want to him to whipe your ass maybe?

Share this post


Link to post
Share on other sites

poor kid can't spell "sentence"

 

so......

 

"Onions are roots, and since photosynthesis is a light-dependent reaction, chloroplasts in onion cells would be unable to produce energy."

 

now bend over.

Share this post


Link to post
Share on other sites
Originally posted by Tesseract

you want to him to whipe your ass maybe?

 

Good to know someone's playing shortstop

while I'm out in left field. Handled perfect.

Share this post


Link to post
Share on other sites
Guest imported_Tesseract

haha, and after take home test was taken care off by people on the internet..lets move to the real question...

 

 

how to make krink?!

Share this post


Link to post
Share on other sites

but.. they will sprout a green leafish thing..

 

once it gets above ground..

 

soo .. is the mystery completely solved or what.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...