Lower Secondary Science

[Verysuperkiasu]

Hope to get an answer by today…


Viruses can be classified on the basis of _______
I. Nucleic acid type
II. Nature of host
III. Capsid symmetry
IV. Presence or absence of an envelope

(a) I and II only
(b) III and IV only
I, II and III only
(d) All of the above

Answer is (d). Why? I, II and II ds can understand. But (IV) - he wants to know what the envelope is referring to. If it’s referring to nuclei, then it’s wrong because all viruses have no nucleus.

[Dr.033430Daniel]

An envelope on a virus is on the exterior. The outermost layer on some viruses. It is made up of material from the host cell membrane. Some viruses like influenza use this strategy, but other viruses do not have an envelope. So it can be used as a way of classifying a virus.

[Dr.033430Daniel]

Gems:

Sorry, we still don't understand the 1st question. How to derive at 1.39? Multiply out could not get the area too. Thanks.

360,000 Pa = 5N/Area

Area = 5N/360,000Pa = 1.39 X 10-5 square meters

Pa is N/m2

there are 100 cm in 1 meter, but 10000 cm2 in a m2. So to convert to cm2 multiply by 10,000 to get 0.139 cm2.

[Verysuperkiasu]

Dr.Daniel:

An envelope on a virus is on the exterior. The outermost layer on some viruses. It is made up of material from the host cell membrane. Some viruses like influenza use this strategy, but other viruses do not have an envelope. So it can be used as a way of classifying a virus.

Thank you., Dr Daniels....


Would appreciate it as I need help for the following questions:

1,The enzyme in pineapple soften meat before cooking. What enzyme function in a similar way in human body? Just to confirm if the answer is 'protease' since meat is protein? or should it by amalyse?

2.Which of the following is true?
a) Bacteria can produce spores.
b) fungi can reproduce by sexual reproduction
c) All viruses have the same capsid symmetry.

Is the answer c)?

[Dr.033430Daniel]

Verysuperkiasu:

1,The enzyme in pineapple softens meat before cooking. What enzyme functions in a similar way in the human body? Just to confirm if the answer is 'protease' since meat is protein? or should it by amalyse?

Right, protease. Protease in the human body works on proteins (found in meat), amalyse breaks down starch into sugars.

[Dr.033430Daniel]

Verysuperkiasu:

2.Which of the following is true?
a) Bacteria can produce spores.
b) fungi can reproduce by sexual reproduction
c) All viruses have the same capsid symmetry.

Is the answer c)?

Were they asking which is not true?

a) true
b) true
c) not true

[Verysuperkiasu]

Dr.Daniel:

Verysuperkiasu:

2.Which of the following is true?
a) Bacteria can produce spores.
b) fungi can reproduce by sexual reproduction
c) All viruses have the same capsid symmetry.

Is the answer c)?

Were they asking which is not true?

a) true
b) true
c) not true

ds can't recall - it was one of his exam questions. BTW, I thought only fungi reproduce by spores.

Thanks anyway!

[Dr.033430Daniel]

Fungi use spores, but some bacteria do also - they are called endospores. Some were found in the tombs of the Eqyptian Pharoahs and when placed in the right environment, they produced the bacteria again. So they are amazingly resilient and can survive for even thousands of years.

[Verysuperkiasu]

Dr.Daniel:

Fungi use spores, but some bacteria do also - they are called endospores. Some were found in the tombs of the Eqyptian Pharoahs and when placed in the right environment, they produced the bacteria again. So they are amazingly resilient and can survive for even thousands of years.

That's interesting piece of information, I must say. Didnt know that before but now I know...thank you for sharing!

[Gems]

Dr.Daniel:

Gems:

Sorry, we still don't understand the 1st question. How to derive at 1.39? Multiply out could not get the area too. Thanks.

360,000 Pa = 5N/Area

Area = 5N/360,000Pa = 1.39 X 10-5 square meters

Pa is N/m2

there are 100 cm in 1 meter, but 10000 cm2 in a m2. So to convert to cm2 multiply by 10,000 to get 0.139 cm2.

Got it. Thank you!