Q&A - P5 Science

[MathIzzzFun]

AgonyMum:

Hi,

Not sure if these are P4/P5 questions...


3. Must oxygen be present in the environment for all eggs to develop?

Thanks in advance!!

hopefully, this helps:

http://www.scientificamerican.com/article.cfm?id=bring-science-home-chick-breathe-inside-shell

http://en.globalquiz.org/question/how-do-baby-birds-get-oxygen-inside-their-eggs/

http://mentalfloss.com/article/31049/how-do-baby-birds-breathe-inside-their-eggs

cheers.

[dioprem]

AtoZ:

Can anyone help on the following:


Mr. Tay has a fruit tree in his backyard that can only bear flowers but not fruits. However, his neighbor's fruit tree produces fruits. Which one of the following could be the most likely reason that explains why Mr. Tay's fruit trees does NOT bear fruits.

1) the tree has male flowers only.
2) the tree has female flowers only.
3) the tree has both male and female flowers.
4) the tree has flowers that have been pollinated already.

Ans key : 4
DD's ans : 1

Can explain why? TIA

Only flowers which have female parts (either bisexual flowers or female flowers) an develop into fruits as they contain the ovary and ovules. So the answer cannot be 4 as if the flowers were already pollinated, they would develop into fruits.

1 makes the most sense as male flowers can never develop into fruits. They can only produce pollen grains to pollinate flowers with female parts.

[dioprem]

PiscesLeo:

http://i47.tinypic.com/t0sykl.png\">


Q1: Explain her observation.
Q2: Predict what she would observe if she placed Cell B in the dish of red and blue dye instead.

Can anyone help? Tks.

1)The fact that the inside of Cell A was stained red implies that the cell membrane of Cell A only allowed the red dye to pass through but not the blue dye. This tests the students ability to apply the fact that the cell membrane is a partially permeable membrane that controls the substances that enter and leave the cell.

2)If Cell B were to be placed in the dyes, the cell would be stained red as well. The only difference between the two cells is the presence of a cell wall. Since the cell wall generally allows anything to enter that the cell membrane allows, we know that the red dye can pass through the cell wall. Even if the blue dye could pass though the cell wall, the cell membrane would not allow the blue dye to pass through it. Hence the cell would be stained red.

Hope this helps.

[marstolive]

Hi, can any kind soul help me with this question? Thanks in advance.



When a cell in placed in a salt solution, it shrivels as water moves out. When it is placed in water, it swells as water enters.

Jim was given some specimens of a certain type of cell. He placed the cells specimen into two different beakers, containing liquid A and liquid B respectively. He then viewed the specimens under a microscope. He recorded the observations made in the chart below.

Observation of cell under the microscope
IN liquid A, the liquid turned red and there was no sign of the cells.
In liquid B, the cells looked all crumpled up.

What could liquid A and B possibly be?

[smartmummy]

hi marstolive!

You may want to post here....
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=68&t=25130&start=190
hope it helps.

[marstolive]

Hi, can any kind soul help me with this question? Thanks in advance.


Hi, can someone help me with this question? Thanks in advance.

When a cell in placed in a salt solution, it shrivels as water moves out. When it is placed in water, it swells as water enters.

Jim was given some specimens of a certain type of cell. He placed the cells specimen into two different beakers, containing liquid A and liquid B respectively. He then viewed the specimens under a microscope. He recorded the observations made in the chart below.

Observation of cell under the microscope
IN liquid A, the liquid turned red and there was no sign of the cells.
In liquid B, the cells looked all crumpled up.

What could liquid A and B possibly be?

[Sun_2010]

marstolive:

Hi, can any kind soul help me with this question? Thanks in advance.


Hi, can someone help me with this question? Thanks in advance.

When a cell in placed in a salt solution, it shrivels as water moves out. When it is placed in water, it swells as water enters.

Jim was given some specimens of a certain type of cell. He placed the cells specimen into two different beakers, containing liquid A and liquid B respectively. He then viewed the specimens under a microscope. He recorded the observations made in the chart below.

Observation of cell under the microscope
IN liquid A, the liquid turned red and there was no sign of the cells.
In liquid B, the cells looked all crumpled up.

What could liquid A and B possibly be?

A = water.
The cells absorbed water , swelled and burst.
B = salt water

[marstolive]

Thanks for your help, Sun-2010! :goodpost:

[Jamesbond]

http://i42.tinypic.com/20jgsa1.jpg\">

Pl answer with explanation....TIA.

[dioprem]

Jamesbond:

http://i42.tinypic.com/20jgsa1.jpg\">

Pl answer with explanation....TIA.

Option A is wrong as the pollen does not travel down with the pollen tube. Rather a pollen tube grows downwards from the pollen grain. The male reproductive cells are at the bottom of the pollen tube.

Option B is correct as that is the mechanism where the pollen grain germinates. The pollen tube attempts to grow towards the ovary where the ovules are contained.

Option C is also correct as the very definition of fertilisation is when the male sex cell fuses with the female sex cell.

So the answer would be (3). Hope this helps