中三bio 問題

2008-06-09 2:29 am

preparing temporary slides of plant cells
1.why is it not necessary to peel off a layer of cells from the hydrilla leaf? Is
that because that hydrilla is multicellular but with simple structure so that
there is only one kind of cells?
2.Why is it not necessary to stain the Hydrilla leaf? Is that because it already
contains chlorophyll and can be seen?
3. Why can we observe pollen grains without stain under the microscope? Do
them contain pigments?
4.Why should we squash the banana tissue before observation?

5.why starch is converted back to sucrose when photosynthesis stops, but not
other form of carbohydrates?eg,maltose
Find the errors in the following statements and correct them.
1.The outermost layer of a cell is the cell membrane
2.All plant cells contain the cell wall and chloroplasts
3.In daytime, carbon dioxide only diffuses into a leaf and oxygen only diffuses
out of a leaf
4.Enzymes are destroyed in an acidic condition
5.enzymes increase the rate of reactions but do not take part in the reactions.
6.only fat or oil can form a translucent spot on a piece of filter paper

回答 (6)

莫愁

2008-06-12 1:40 am

✔ 最佳答案

1.A slide should contain the whole structure of a sample you want to
observe. If you just peel off a layer of cells, what it contains should
be CUTICLE only. Since it is difficult for you to separate palisade
,spongy mesophyll and chlorophyll only without the help of electron
microscope.

2.You have already answered.

3.They are very small and not pigmented. In spite of small size, we can
see them with our eyes. Observing them through microscope is to find out
if their outer surfaces, exine , contain hooks (spine) or not.

4. After squashing the banana tissue, it can easily be placed between
microscope slide(大size) and the cover glass(細size) for observation
under microscope.

5.The actual reason, I do not know. But what I know is sucrose can induce a
mass flow in the sieve tube of phloem instead of glucose and maltose.

Corrections:
1The outermost layer of a cell is the cell membrane.
1The outermost layer of an animal cell is the cell membrane
2All plant cells contain the cell wall and chloroplasts.
2Some plant cells contain the cell wall and chloroplasts such as dodder
leaves without chloroplast but with cell wall .
3In daytime, carbon dioxide only diffuses into a leaf and oxygen only
diffuses out of a leaf
3*In daytime, when light intensity is high, carbon dioxide only diffuses
into a leaf and oxygen only diffuses out of a leaf.
4.Enzymes are destroyed in an acidic condition
4.Enzymes working in alkaline condition such as trypsin are destroyed
in an acidic condition
5.enzymes increase the rate of reactions but do not take part in the reactions.
5.enzymes increase the rate of reactions and take part in the reactions.
6.only fat or oil can form a translucent spot on a piece of filter paper
6.only lipid can form a translucent spot on a piece of filter paper

Additional information:
3* When in winter and raining day, with light intensity lower than 10000
lux(流明度), carbon dioxide when be produced by cellular respiration due
to rate of photosynthesis is lower than that of respiration.

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惠楠

2008-06-10 2:23 am

我覺得你地唔應該咁樣"蝦"阿Tom
佢只係發表個人o既意見
根本沒有錯
而且你地咁樣會hurt 到人
004and006,你地話人地唔識字,請問你地係哩生人中,未打/寫錯字咩???你自己又何嘗唔係打錯個"科"字ar!!!!!!!!!!!

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[匿名]

2008-06-10 1:24 am

同意003同004既講法.
呢個人好有問題,
一開口就鬧人,
快D送入青山精神料..!!!

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用戶202490

2008-06-10 1:15 am

回#002

係搭嗲=,=
字都唔識多隻就學人踩人
真係好笑

多數有問題既人都話人地有問題
洗唔洗幫你打去青山精神料?