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A boatload of botany questions

Posted by riverminty (My Page) on
Mon, Oct 12, 09 at 23:32

I hate to be one of those who takes their homework questions and tries to pawn them off on this website, but a number of these questions are NOT clearly explained in my textbook. It's very frustrating. So, I'm going to try here. There are a lot, on several different subjects, some pertaining to biology or chemistry in general and not necessarily just botany. Any help would be GREATLY appreciatied.

They are multiple choice. Here we go....

1. What must occur in binary fission before the cell can divide (my money's on B or D)?

a: The chromosomes must be replicated
b. The chromosome must be replicated
c. The nucleus must be replicated
d: The septum must form

2. If one species has a higher chromosome number than another species, must it also have more genes (my money's on D)?

a. Yes, because genes are roughly the same length
b. Yes, even though the chromosomes can be different lengths
c. No, since genes can be very different lengths
d. No, because the chromosomes are different lengths

3. After the DNA is replicated during the S phase of interphase, why doesn't the cell simply enter mitosis?

a. Genes necessary for division must first be synthesized
b. Proteins and other structural components must still be synthesized before division occurs
c. The chromosomes must also be replicated in the G2 phase
d. It does; the S phase is the last phase of interphase

4. Since there are 20 different aminoa acids, and tRNA is the molecules that brings an amino acid to the ribosome during translation, why are there over 60 different tRNA molecules instead of just 20?

a. The 3 types of ribosomes in the cells (in organells, on rough ER, free in the cytoplasm) each have their own set of tRNA molecules
b. The extra tRNA molecules are coded for by introns
c. Amino acids can undergo conformational changes, and several tRNA moleucles code for different conformations on the same amino acid
d. None of the above

5. Why are prokaryote genomes so much smaller than eukaryote genomres?

a. Prokaryotes lack introns
b. Prokaryotes lack exons
c. Prokaryotes are smaller, so they have fewer genes
d. Prokaryotes are much simpler than eukaryotes, and lack the specialization for which large numbers of genes would be required

6. Which of the following is a true statement (it seems a and d are both correct!)?

a. Prokaryotes lack sexual reproduction
b. Prokaryotes readily undergo meiosis
c. Prokaryote gametes fuse to form zygotes
d. Prokaryotes have a means of genetic exchange

7. If you treated an organism a chemical that inhibited microtubule formation in the cells that form gametes, after three generations what would the offspring's chromosome number be (my money's on c)?

a. 2N
b. 16N
c. 8N
d. N

8. Which of the following is a true statement?

a. Meiosis works by separating pairs of homologous chromosomes
b. Since the ovum is larger it contributes he greater number of chromosomes
c. During meiosis chromosomes assort so all male derived chromosomes end up in one gamete
d. None of the above

9. You are studying sporangial developement in a fern that has a diploid chromosome number of 30. How could you tell is meiosis has occuring in the sporangium (my money's on a)?

a. There would be four times the number of cells, each having 15 chromosomes
b. There would be twice the number of cells, each having 30 chromsomes
c. There would be the same number of cells, each having 30 chromosomes
d. There would be twice the number of cells, each having 15 chromosomes

10. Humans and most other animals have which type of life cycle?

a. Gametic
b. Sporic
c. Zygotic
d. Meiotic

11. In organisms with a zygotic life cycle, crossing over would occur in

a. The hyphae
b. The spores
c. The gametes
d. The zygote

12. Why are arginine and glycine considered to be nonessential amino acids?

a. Vitamin supplements contain adequate amounts of these compounds
b. They are plentiful in our diet
c. They are nore needed for proper cell function
d. Our bodies can produce them from other amino acids

13. You are working for a nutriecutical company and have found a new plant secondary compound in an extract from a rain forest plant. THe chemical composition of the compound is C8H8O3. You conclue that

a. The compound is a terpene because it contains oxyten
b. The compound cannot be a flavonoid because it has an even number of carbon atoms
c. The compound cannot be an alkaloid because it contains no nitrogen
d. The compound cannot be a phenolic because phenolics lack hydrogen

I KNOW this is a lot, but if you could try and answer most of them, I would be really, really, really grateful. And if you could please, please please, try and resist giving me links to try and answer certain questions, and just type the answer yourself if you know it? Please?

Thank you!!!!

Follow-Up Postings:

RE: A boatload of botany questions

Worrying to realise how much of this I've forgotten!!

1 a, maybe also c
2 c and d ??
5 d
6 agree does seem to be a and d
7 probably dead ;-)
8 a (I think!)
9 a (I think!)
12 d
13 c

RE: A boatload of botany questions

riverminty, welcome to the world of learning. It is strewn with questions. These can be answered and/or explained. You will choose which you want and you will find your particular response. I wish to commend to you the Chinese proverb, "Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime."
Learn to research. You will need the ability for the rest of your life.

RE: A boatload of botany questions

When I was a teenager, my bio teacher told me prokaryotes can reproduce sexually, but now I'm not sure if she was referring to plasmid exchange.

I have another botany question: is "polyembryonic" synonymous with "chimeric"?

RE: A boatload of botany questions

  • Posted by brandon7 6b (like 7b now) TN (My Page) on
    Tue, Oct 20, 09 at 9:44

I was thinking just what Ronalawn82 wrote, but could not have expressed nearly as well.

Joanie, I'm wondering if there is something more to your question than first appearance or if the question is misworded. The terms "polyembryonic" and "chimeric" are completely different. And, unless I'm missing something, I don't even see any similarities.

RE: A boatload of botany questions

I was confused about whether a polyembryonic seedling was the result of many embryos combining into one organism.1 Mostro said the sprouts from a polyembryonic seed are their own organisms, so that would be a no. So the remaining question is: are all the embryos in a polyembryonic seed identical? I read somewhere that if polyembryonic seedlings are allowed to remain together, they don't need a pollenizer, so I suppose that would be a no, too, but I don't know if whoever wrote that had any experience or academic knowledge of such things. (Besides, don't plants know who their siblings are?)

1. While we're on the subject, is there a word for this that distinguishes it from other forms of chimerism, such as maternal stem cells joining with fetal stem cells?

RE: A boatload of botany questions

I have read online some time ago that citrus seeds are polyembryonic and that only one seedling was the result of cross pollination. The others are supposed to be identical to the mother plant. I don't have any journals or support, bust I'm just throwing it out there if it. Chunerism I believe, is when the parent cells fuse and every one keeps their own traits. The resultant is something that is not as stable genetically. Some cannas exhibit chimerism and are prized for this genetic unstability because each leaf may be different.

RE: A boatload of botany questions

  • Posted by brandon7 6b (like 7b now) TN (My Page) on
    Wed, Oct 28, 09 at 9:35

Polyembryonic plant seedling are the result of a single fertilized egg splitting into two or more identical embryos (similar to polyembryony/identical-twining in animals) . The result is genetically identical offspring, and those offspring would only be sexually compatible if the individuals themselves were self-fertile.

Chimerism is the combining of two or more genetically different groups of cells.

BTW, interesting article about plant sibling recognition, but I don't think it has anything to do with whether polyembryonic plants are sexually compatible.

RE: A boatload of botany questions

Origami, were you referring to this?

Brandon, are you sure you don't mean that only the embryos from the maternal cells are identical? That would explain why two self-sterile adults from the same seed can cross-pollinate, if they need only to be nonidentical, not dissimilar.

RE: A boatload of botany questions

Brandon is referring to the case where multiple embryos are all derived from the same zygotic embryo (cleavage polyembryony). All the embryos would therefore be genetically identical.

I believe you are thinking of the situation where multiple egg cells within the same ovule are fertilized independently (simple polyembryony). Typically the eggs are all derived from the same cell, but provided the male donated gametes are different the resulting embryos would not be genetically identical.

Either, neither, or both can occur in the same seed. Most often only the dominant embryo survives. Chimerism is very unlikely to occur under natural conditions but may arise when embryogenic cultures are established from polyembryonic seeds.

RE: A boatload of botany questions

Actually, I was referring to the opening of the article I cited. "Citrus exhibits polyembryonic seed development, an apomictic process in which many maternally derived embryos arise from the nucellus surrounding the developing zygotic embryo." (Emphasis mine)

Also, according to EXTENTO, "Polyembryonic mango varieties, like the so-called common or Hawaiian mango varieties, produce two or more plants of nucellar (maternal) origin from each seed. These plants are predominantly true to type, and may be grown from seed without the necessity of grafting."

So I suppose now I'm left with the question of whether the nucellar embryos are clones or parthenogenic. I'd probably know that if I paid more attention to biology in high school. Is the nucellus haploid or diploid?

RE: A boatload of botany questions

The nucellus is derived from sporophyte tissue so it is diploid. The nucellus normally produces a megasporocyte which eventually undergoes meiosis to form four megaspores. Usually only one of the megaspores survives to become the female gametophyte that subsequently produces eggs.

When embryos are derived from the nucellus it is called nucellar embryony, a type of sporophytic apomixis. These would be clonal because they are produced asexually. This is different from parthenogenesis which is when an embryo forms from an unfertilized egg.


Unfortunately they don't allow you to edit posts here. I should probably clarify that both apomixis and parthenogenesis both produce offspring asexually. The only difference is the donor tissue.

RE: A boatload of botany questions

Thanks. I could really use a refresher course!

RE: A boatload of botany questions


RE: A boatload of botany questions

pennyroyal1961, I don't have a good answer but I found some interesting tricks which flowers play on bees at this site..

RE: A boatload of botany questions

  • Posted by brandon7 6b (like 7b now) TN (My Page) on
    Mon, Nov 16, 09 at 15:37


I noticed you're new to Gardenweb. Welcome and I hope you find it to be a helpful and fun place.

I don't have any answer to your bee question, but would like to offer three suggestions:

1) Please start your own thread when asking questions not directly related to the original post. There are many reasons for this including:
a) It's very confusing when someone starts there own conversation within another conversation.
b) The original poster is now getting responses to your post emailed to them, clogging up their email with answers to your question.
c) You are not getting the answers emailed to you because your question is in another thread.
d) It is much harder to find information when searching for information when threads have multiple topics intermixed.

2) Try to post your questions to relevant forums. For instance you could post your question above to the Bees & Beekeeping Forum (linked below).

3) Don't type in all caps. It is considered rude and/or shouting by many.

Here is a link that might be useful: Bees & Beekeeping Forum

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