Science Buddies: "Ask an Expert"

For my science fair project my friend and I are extracting DNA from fruits and vegetables. We already know how to do the experiment but we are stuck on a question that we are going to be solving. Our current one is "Which has more DNA, fruits or vegetables?" but it's not that good of a question.
We were deciding on doing our experiment in 2 days and still need a question. If someone could help me soon, that would be greatly appreciated cause it is due in 2 weeks.
Thanks!

Hi!

I'm not an expert, but I've been in a similar situation and empathize.

First, check out the Science Buddies link on choosing a question for a science fair project: https://www.sciencebuddies.org/science- ... tion.shtml

Since you already have chosen a topic, skip down to the Your Science Fair Project Question section.

Some points you should consider while choosing a question can include:
- variables (https://www.sciencebuddies.org/science- ... bles.shtml)
- availability of materials
- information in books/journals/online based on the subject

Good luck!

Thanks for your help, but I'm still stumped..
I will keep looking.

Hi!

Don't get discouraged!

Note that the question whether fruits or vegetables have more DNA is NOT a bad question at all! I actually find it EXTREMELY interesting! To have a better quality of experiment/understand and to impress judging, it will be amazing if you could say WHY _____ has more DNA than _____. This will need to you to do some background research.

Get familiar with the terms: lipids, cell membrane, protein, DNA, precipitate, fruit and vegetable cells. Have you read up on your subject yet?

Good luck!

Hi,

Irregular has already given you some good advice! Your question is fine, but he is right that you want to do some more background research and determine -why- fruits might have more DNA than vegetables or vice-versa. Keep in mind that, by definition, fruits are reproductive bodies, whereas vegetables are not. You might therefore look up more information about plant reproduction.

One variation on a project like this--which is an active area of inquiry in science--is to think about how different varieties of the same species could have different DNA. For example, did you know that broccoli, cauliflower, turnips, kholrabi, brussels sprouts, and cabbage all come from different varieties of the same species? It might be interesting to see whether you see any differences in amounts of DNA between these plants which have been artificially selected by humans for different traits.

That sounds great, and yesturday I thought up about a question and came up with "does the different type of fruit or vegetable effect the amount of DNA it produces?" It is sort of like you were saying. But about the amount of DNA, my mom says that in people no one has more DNA than another person. So, I was wondering if it would be the same with plants.

Thanks for your help, and I'm gonna go some more research to see what I can find out. If you think of anything better please let me know.

Your mother is actually not right. For example, she has more DNA than you do, because she's female--and has two X chromosomes, whereas you have an X and a Y. Since the Y chromosome is smaller, women have more DNA than men. Also, people with Downs' Syndrome and other similar genetic disorders often have more or less DNA than the average person.

But, on average, ignoring the difference between men and women, yes, humans have about the same amount of DNA. That's because we're all the same species! However, plants can have vastly different amounts of DNA depending on what sort of plant it is. Many plants speciate when they end up with 4 or 8 copies of various chromosomes instead of 2. So, you should be able to see differences as long as you test many different kinds of fruit and vegetables.

Good luck!

Okay, thanks.

okay, we have started our experiment, we decided too do 2 of each fruits and vegetables of each type, resulting in 24 experiments. We were just wondering how this experiment would help humans today. If there is nothing it is fine.
thanks

The experiment you are doing falls into a category that scientists call 'basic research'. What this means is that this is research that isn't designed for a specific purpose--like helping humans. However, basic research can yield important insights that can lead to applied research. So, for example, you might find that by finding the amount of DNA you can tell species apart--which might turn into an important way of identifying plant material with further research. But, you won't know until you do the experiment!

Good luck!

okay cause alot of people were asking us how it would help humans, and now we know how too tell why. we have already tested all of our fruits, and intotal it took us about 6 hours because each test takes about a half an hour, and we did 12 fruit tests. And we found that the ones with Vitimin C had more DNA than the other fruits. Today we are going too be testing the vegetables, so hopfully we have a good out come !
thanks again.

so.. do you think that it would be true that the fruits or vegetables with the most DNA happened because of vitamin C ?

Whoops, sorry that no one has replied to your post yet.

No, I don't think that fruits contain more DNA because they have Vitamin C in them. I suspect that citrus fruits are simply polyploid: http://en.wikipedia.org/wiki/Polyploidy and that most citrus fruits are related .

thanks.
umm. personally do you think vegetables have more DNA than fruits, or do you think fruits have more DNA than vegetables ?
also do you think there is a logic answer for fruits have more DNA than vegetables, or vise versa ?
thanks again [*]

Question, we are sortof in a puzzel on how we would be able to compare the DNA that the fruits and vegetables produced...

I don't have a hypothesis for which would have more, because I haven't done enough background reading. What I would do is look up what sorts of plants we get vegetables and fruits come from, and then see how many copies of each chromosome the various plant groups have. My own hypothesis is that I would extract more DNA from plants with more copies of each chromosome.

As for the comparison, you compared citrus fruits with other fruits and decided that citrus fruits had more DNA, right? You do exactly the same sort of comparison between your fruits and vegetables. Or, is there variation in your sample? Do some fruits have more DNA than the vegetables and other fruits have less? Let us know what your results were and we can try to help .

Is this good? Cause our science fair is tomorrow...?
Results:
The results were unpredictable. It ended up that the fruits did have more DNA than the vegetables but not by far. For the different types of fruits and vegetables, the Tropical and Exotic with banana and mango did the best, looking at what ranking they came in and if it beat the vegetable it was against. But when it comes to seeing which fruit or vegetable has the most DNA, it would be Plum because it had the most DNA out of all the fruits and when we compared it to the vegetable that had the most DNA out of all the vegetables, the Plum had more.

We took a look at the tests that we did and we ordered the fruits and the vegetables from the most amount of DNA to the least. We did this by what we thought looked like had more or less DNA. Then we compared the 1 fruit and the 1 vegetable with the same ranking to see which had more DNA. Below is our ranking from the most amount of DNA to the least with the comparison between the fruits and vegetables.

Fruit Rankings Vegetable Rankings
1. Plum  1. Lettuce
2. Banana  2. Cabbage
3. Strawberry 3. Zucchini 
4. Orange  4. Garlic
5. Honeydew Melon  5. Celery
6. Mango  6. Cucumber
7. Watermelon  7. Onion
8. Kiwi 8. Yam 
9. Peach 9. Potato 
10. Lime 10. Asparagus 
11. Apple  11. Broccoli
12. Pear 12. Spinach 
 = Won Against the Same Rank
7/12 5/12

Total Ranking
Fruit and Vegetable Ranking

1. Plum
2. Lettuce
3. Banana
4. Cabbage
5. Zucchini
6. Strawberry
7. Orange
8. Garlic
9. Honeydew Melon
10. Celery
11. Mango
12. Cucumber
13. Watermelon
14. Onion
15. Yam
16. Kiwi
17. Potato
18. Peach
19. Asparagus
20. Lime
21. Apple
22. Broccoli
23. Spinach
24. Pear

Also they are in colours that determine what type of fruit/vegetable that they are but it doesnt show on here. And they are in tables.

I'm not sure if I'm too late or not, but this looks great! It's definitely an interesting result. Remember, your results are your results--they don't have to match your hypothesis for the experiment to be a good one!

Congratulations on the successful science fair project, and if you haven't already presented, good luck at the fair!

Hi!

I am also actually doing a similar experiment and I was also stuck on the same problem, finding an objective until I saw this post. Since I am also using the same problem, it would help if I knew what fruits and vegetables you used. So far, i am planning to use Strawberries, however, I don't know what other fruits and vegetables to use...I am planning to use 3 types of fruits, and 3 types of vegetables. So I hope you can help me!

Hi DNAbasics,

You should use any type of vegetable or fruit you like. It really does not matter because in the long run, the most interesting research project for you will be the one that incoporates the DNA content of the fruits and vegetables you like.

Hope that helps!

-Sam

Hi,

Thanks for the help, I picked strawberries, pears, kiwi, cucumbers, potato and lettuce. I am planning to use 30 grams of fruit and vegetables and i am doing 3 trials for each however, I do not know how much fruit and vegetables I should buy, hope you can help me on this!