Help for Bio p2

[Snowberry]

Diffusion and Osmosis;

Describe the importance of a water potential gradient int he uptake of water by plants and the effects of osmosis on plan and animal tissues.


Animal Nutrition:

Explain why most foods must be digested.



Transport in Flowering Plants:

Describe How wilting occurs.



Transport in Humans:

Describe the transfer of materials between capillaries and tissue fluid.



Respiration:

Describe the effect of lactic acid production in muscles during exercise.

Excretion:

Describe the removal of carbon dioxide from the lungs.



Reproduction;

Describe and Name one commercially important application of asexual reproduction in plants.

State the role of mitosis in growth, repair of damaged tissues, replacement of worn out cells and asexual reproduction.

Compare male and female gametes in terms of size, numbers and mobility.

Inheritance;

Distinguish between the term Gene and Allele,

Explain why observed ratios often differ from expected ratios, especially when there are small numbers of progeny.

Describe Variation

Discuss potential advantages and dangers of Genetic Engineering.




Thanks

 

[Shiki Misaki]

Diffusion and Osmosis;

Describe the importance of a water potential gradient in the uptake of water by plants and the effects of osmosis on plan and animal tissues.
In the uptake of water by plants, water potential gradient predicts the direction in which the water will flow, according to the concentration of the solute. Osmosis is the movement of water molecules from a solution of a higher water potential to a lower water potential across a semi-permeable membrane. Animal cells will shrink and have little spikes appear on the cell surface membrane when placed in a solution of low water potential. The crenated cell will become dehydrated and eventually die. When placed in a solution of high water potential, they will swell and burst.

Animal Nutrition:

Explain why most foods must be digested.
Digestion is important to break down large pieces of food so as to increase its surface area to volume ratio for enzymatic action and also for absorption. Organs that form part of the digestive system are the mouth, oesophagus, stomach, small intestine, large intestine. Nutrients like carbohydrates, fats, protein and fat-soluble vitamins (A, D, E, K) need to be digested. The broken down food are carried off in the bloodstream to other parts of the body for storage or further chemical change.


Transport in Flowering Plants:

Describe How wilting occurs.
When rate of transpiration exceeds rate of absorption, it causes wilting. When a plant loses water from the leaves and the stalk due to excessive transpiration, and this water cannot be replaced, the leaf cells lose their turgidity and become plasmolysed. As a result, the tissue becomes flaccid and this will result in wilting. Wilting will occur when the atmospheric temperature is high, windy, low humidity and the light intensity is high as well as low water content of the soil. All these factors will increase the rate of transpiration.



Transport in Humans:

Describe the transfer of materials between capillaries and tissue fluid.
Substances pass through the capillaries wall by diffusion, filtration, and osmosis. Oxygen and carbon dioxide move across the capillary wall by diffusion. Fluid movement across a capillary wall is determined by hydrostatic and osmotic pressure.


Respiration:

Describe the effect of lactic acid production in muscles during exercise.
Accumulation of lactic acid in the muscles during vigorous exercise causes cramps and it is not secreted as it still contains energy. It is eventually carried in blood to the liver where it is converted into glucose. After exercise, breathing rate remains high as additional oxygen must be supplied to oxidise the lactic acid and to replenish oxygen stored in the body. When the body lacks oxygen and carries out anaerobic respiration, this is called an oxygen debt. the oxygen debt is repaid after exercise when breathing rate remains high.



Excretion:
Describe the removal of carbon dioxide from the lungs.
Through the process of gaseous exchange; air is warmed,moistened and cleaned as it is drawn into the nasal passage by mucus in the trachea. This moistened air then enters alveoli where gaseous exchange occurs. Around each alveolus there is a series of capillaries, Oxygen dissolves in to a moisture lining in the alveolus and then in to the red blood cells while carbon dioxide diffuses out of the plasma and red blood cells which is then removed from the body by expiration.


Reproduction;

Describe and Name one commercially important application of asexual reproduction in plants.
Potato. It reproduces by budding. Cells in the bud or stem divide many times by mitosis, producing many identical cells. Eventually, the bud or stem separates from the parent plant to form a new plant. [Ref: Biology Matters, Eric Y K Lam]


State the role of mitosis in growth, repair of damaged tissues, replacement of worn out cells and asexual reproduction.
Mitosis is the type of division that gives rise to daughter cells for the purpose of tissue growth, regeneration or asexual (vegetative) reproduction.
Growth - multicellular organisms increase their size through growth. This growth involves increasing the number of cells through mitosis. These cells will differentiate and specialise their function.
Tissue Repair - As tissues are damaged they can recover through replacing damaged or dead cells. This is easily observed in a skin wound.
Asexual Reproduction - This the production of offspring from a single parent using mitosis. The offspring are therefore genetically identical to each other and to their 'parent' (clone).



Compare male and female gametes in terms of size, numbers and mobility.
The head of the sperm(male gamete) is about 2.5 micrometres wide. Flagellum is also part of it enabling it to swim towards the egg. The ovum (female gamete) is about 120 micrometres wide. Male gametes are smaller than female gametes and are produced in much larger numbers than female gametes. Male gametes are motile whereas female gametes are non-motile.


Inheritance;

Distinguish between the term Gene and Allele,
A gene is a segment of DNA which codes for a polypeptide(protein) which in turn controls a particular characteristic in an organism. Alleles are different forms of a gene.


Explain why observed ratios often differ from expected ratios, especially when there are small numbers of progeny.
P.S: Are you sure this is in our syllabus? :S


Describe Variation.
Variation means divergence in one or more characteristics of an organism.

P.s: If you're referring particularly to genetic variation, then it is the measure of the genetic differences there are within populations or species.


Discuss potential advantages and dangers of Genetic Engineering.
Advantages :
Genetic engineering can produce crops with greater yields, make plants or animals disease-resistant, enable crops to grow in poor soils, provide genes that overcome a disorder.


Disadvantages:
It is costly, unexpected or undetected mutations can take place.

 

[Snowberry]

Merci ^^

 

[Pals_1010]

Explain why observed ratios often differ from expected ratios, especially when there are small numbers of progeny.

This is because the fusion of gametes is a purely random process and so when involved with small numbers, inaccuracy occurs with the expected ratios

 

[Shiki Misaki]

Anything for you. ^^