Science & Mathematics - 9 October 2006

In species that exist as separate male- and female plants, presumably the pollen will come from the male plant, while the seed will develop in the female plant. How can this seed coming from the same female plant develop in separate male- and female plants?
I can see 2 possibilties:
1.
The female flower produces both male- and female seeds. If so, what causes the differentiation between those two kinds of seed, when they develop in the female plant?
2.
The female plant makes only one type of seed that differentiates in male- and female plants only after germination. If so, what causes this differentiation?

Which of these 2 is the right answer?

Louis Harmsen

2006-10-09 08:01:26 · 3 answers · asked by Anonymous in Botany

I want a complete and schematic diagram showing earthworm's circulatory system, so that i can understand it in a better way and prepare well for my exams.

2006-10-09 08:00:41 · 4 answers · asked by sharat_vishwanath 1 in Zoology

A 8.50 kg block (m1) and a 7.55 kg block (m2) rest on a horizontal frictionless surface with m2 resting on top of m1. The surface between the top and bottom blocks is roughened so that there is no slipping between the two blocks. A 42.6 N force is applied to the bottom block.

What is the acceleration for the two block system?

What is the force of static friction between the top and bottom blocks?

What is the minimum coefficient of static friction necessary to keep the top block from slipping on the bottom block?

2006-10-09 07:58:59 · 1 answers · asked by gunder53534 2 in Physics

2006-10-09 07:57:28 · 3 answers · asked by Justin S 1 in Engineering

...find the angular width of the pencil, in minutes of an arc.

Please show your work because I am having a lot of trouble understanding and figuring this out. Thanks a whole lot!

2006-10-09 07:56:34 · 2 answers · asked by hunnnnk 1 in Astronomy & Space

and threw them into the air...which one would land on the floor ?

2006-10-09 07:56:29 · 5 answers · asked by (\ G®1M R34|Dê® /) 4 in Other - Science

...and also, would the star be visible to the naked eye?

2006-10-09 07:54:15 · 1 answers · asked by hunnnnk 1 in Astronomy & Space

2006-10-09 07:50:41 · 7 answers · asked by pleasebenice 2 in Biology

Please show all work so I can understand better. Thanks a lot!

2006-10-09 07:50:12 · 5 answers · asked by hunnnnk 1 in Astronomy & Space

2006-10-09 07:48:45 · 5 answers · asked by bhulokaramanna 2 in Mathematics

Please show all work using Scienfitic Notation. Thanks!

2006-10-09 07:45:45 · 8 answers · asked by hunnnnk 1 in Astronomy & Space

An electron that is expelled from the back of a T.V is traveling at about 3.4000m/s horizontally toward the front of T.V screen which is on average 0.45m away. How far does the electron drop before hitting the pixels on the T.V to cause a fluorescence of the pixel on the front( a color TV)

2006-10-09 07:44:52 · 3 answers · asked by water yu 3 in Physics

i have made a project called MICRO-POWER FLASHER.In this project i have used IC CD4093,but i don't know how the IC work.

2006-10-09 07:44:48 · 3 answers · asked by Shibasish 1 in Engineering

r(t) = ((2^(1/2))t)i + (e^t)j + (e^-t)k is a given verctor-valued function with domain ranging from 0 to 6... I have to find the length of arc... formula for it is...

s = int ( norm ( deri ( r(t)))) with respect to t... upper and lower bounds are given 6 and 0...

r'(t) = (2^(1/2))i + (e^t)j - (e^t)k

||r'(t)|| = (2+(e^4t)+(e^-4t))^(1/2)

when I simplify it, I get...

||r'(t)|| = ((e^2t)+1)/(e^2t)

I am sure I have not made mistakes in simplifying, right???

once I integrate the norm of derivative of r(t), I get...

(t+((e^-2t)/-2))... once I apply limits, my answer should be...

13/2 - (e^-12/2)...

so my basic question is, anyway i can simplify this???

btw my given options are following...

1. e^6 +e^-6
2. 2e^-6
3. 2e^6
4. e^6-e^-6
5. e^6

which one am i choose?

2006-10-09 07:44:21 · 3 answers · asked by Faraz S 3 in Mathematics

hey can yall help me w/ sum chemistry problems? here they are:

what element in the periodic table has 6 electrons in their outer energy level?

what is the largest element in row 4....xcept 4 noble gasses?

what is the smallest element in row 3......excluding the noble gasses?

2006-10-09 07:43:52 · 3 answers · asked by tracklurver09 3 in Chemistry

2006-10-09 07:43:03 · 13 answers · asked by (\ G®1M R34|Dê® /) 4 in Biology

Why do we have organs?

Do you hate having a body that has organs inside of it?

What is the meaning of being alive?

Do you believe in God?

Is heaven and hell are real places for dead people?

2006-10-09 07:42:51 · 11 answers · asked by D.J 5 in Biology

why isn't there any protective covering on the high tention power lines out side..any answers?

2006-10-09 07:41:40 · 7 answers · asked by tazzle 2 in Engineering

2006-10-09 07:41:08 · 2 answers · asked by I.Like.To.Disco 1 in Biology

Does anyone know any good chemistry labs/ experiments pertaining to food chemistry and different techniques of cooking? It needs to be high school level chemistry.

2006-10-09 07:41:07 · 2 answers · asked by Kate 2 in Chemistry

i would like to know how you mine the mineral quarts.

2006-10-09 07:40:44 · 5 answers · asked by Anonymous in Earth Sciences & Geology

School

2006-10-09 07:39:50 · 13 answers · asked by sk8eninvans 1 in Other - Science

If people are going repeat the same question about the chicken and egg, then I'm going to ask so many "what came first questions".

2006-10-09 07:39:13 · 2 answers · asked by Anonymous in Biology

2006-10-09 07:37:33 · 15 answers · asked by third_day_rockz 1 in Geography

I need to make one for physics and I'm not good with science or engineering. I have no idea where to start. I have about 3 weeks to make this thing so any help would be greatly appreciated.
It needs to launch a ping pong ball 4 meters into a basket with sides about 18 inches high.
Please include websites with designs if possible. I have **no** money to spend on books and very little for materials.

2006-10-09 07:36:25 · 8 answers · asked by part_cat 1 in Physics

2006-10-09 07:35:17 · 11 answers · asked by (¯`·.ÐåRk~®Âñ§lë.·´¯) 1 in Biology

2006-10-09 07:33:48 · 6 answers · asked by la l 1 in Astronomy & Space

I posed a question last week regarding a large moth as I presumed. The answers came back that moths can't close their wings as I had stated this one had. On checking further sites I realise that closed wings may mean together in a vertical position. This is not what I meant as this one layed its wings down its back. Since then I have found another slightly smaller one, which I have photographed ( against a rule) and it is between 2.5 and 3 inches long (head to wingtip layed down its back). I am no nearer solving what it is and wonder with this clarified info if there are any further answers. The latest one was found on the grass where the previous one was on a car tyre. I put it into a hanging basket where it buried itself deeper and then disappeared overnight.

2006-10-09 07:32:47 · 6 answers · asked by Anonymous in Botany

2006-10-09 07:28:36 · 12 answers · asked by Anonymous in Other - Science

IO4- + I- + H+---> I2 + H2O (all #s denote subscripts)

Please explain how you got to each step...how you balanced it, then how you ultimately identified the oxidizing and reducing agents. Thank you.

2006-10-09 07:26:49 · 2 answers · asked by Anonymous in Chemistry