Chapter 6.10: Photosynthesis

1.  What are the substances needed for photosynthesis?

     Carbon dioxide, water and light energy.

2.  What types of cells make up the mesophyll? Explain their roles in photosynthesis.

images.yourdictionary.com

      a) palisade mesophyll : contains high density of chloroplast to receive

         the maximum   amount of light.

      b) spongy mesophyll  : loosely arrange and have large air spaces

           between the cells to allow easy diffusion of water and carbon dioxide

            through the leafto the palisade cells.

 

State two differences between a palisade cell and a spongy mesophyll cell.

PALISADE CELL	SPONGY MESOPHYLL CELL
1.  filled with chloroplasts	1.  contain very few chloroplasts
2.  closely packed	2.  loosely packed

Paper3: BOD Level

Example of report writing

Problem statement :

What is the level of water pollution in different sources of river water?

Aim of investigation :

To determine the level of water pollution in different sources of river water

Variables :

Manipulated:     the sample of water from different rivers

Responding:      time taken for methylene blue to decolourise

Control:             volume of water sample //volume of methylene blue//concentration of methylene

                          blue

Statement of hypothesis:

The time taken for the methylene blue solution to decolourise with the water from river A is faster than with the water from river B.

List of apparatus

(250ml) reagent bottle with stopper, beaker, syringe, stopwatch

List of materials

Water sample(at least 4 type), methylene blue solution(0.1%)

Technique used

Record the time taken for methylene blue to decolourise by using  a stopwatch.

Experimental procedure

 

1. Water samples are collected from four  different rivers.      ( Distilled water is used as a control). (K1 +K4)
2. Four reagent bottles are labelled as A,B,C, D and E. (K1)
3. Each reagent bottle is filled with the following water sample. (K4) (at least four water samples)

A-water from river 1 (or place A etc)

B-water from river 2

C-water from river 3

D-water from river 4

E- distilled water

4. 1ml of methylene blue solution is added (K2) by using a syringe (K1) to the base of each water sample (K5) in each reagen bottle. (K1)
5. Each reagent bottle is then closed quickly with a stopper (K1).
6. The reagent bottle cannot be shaken. (K5)
7. Each reagent bottle is kept in a dark place(cupboard) (K1) and then the stopwatch is started. (K3)
8. The bottles are examined from time to time. (K1)
9. The time taken for methylene blue to decolourise is recorded (in a table for all water sample) (K3)

Presentation of data

Data is presented in a table with correct title & unit

Source of water	Time taken to decolourise methylene blue solution (minutes or hours)	Level of water pollution
A
B
C
D
E

Conclusion :

The time taken for the methylene blue solution to decolourise with the water from river A is faster than with the water from river B.

Chapter 5: Cell Division

Able to state two characteristics of daughter cell when parent cell undergoes Mitosis process based on :

• Number of chromosomes
• Genetic content

Sample answers:

-The daughter cell has similar number of chromosomes to the parent cell

- The daughter cell has similar genetic content to the parent cell

Able to state what happens in the cell during interphase.

Sample answers :

· Protein is synthesised, number of organelles increases and energy is storaged

· Replication of DNA

· Final preparation of cell for cell division to take place //synthesis of cellular materials// mitotic spindle begins to form// Energy storage increases

Able to describe the behaviour of chromosomes during prophase, metaphase, anaphase and metaphase using suitable diagrams.

Prophase ;

The chromosomes in the nucleus condense and become more tightly coiled.  They appear shorter, thicker and are visible under the light microscope.

Metaphase :

Chromosomes are line up on the metaphase plate

The two sister chromatids are still attached to one another at the centromere

Anaphase :

The two sister chromatids of each chromosome separate at the centromere

The sister chromatids are pulled apart to the opposite poles by the shortening of the spindle fibres that connect  chromosomes to the poles

Telophase :

Begins when the two sets of chromosomes reach the opposite poles of the cell.

The chromosomes start to uncoil and revert to their  extended state ( chromatin ).

The chromosomes become less visible under the microscope.

Able to state the important of mitosis

Sample Answer :

1. in growth process // to increase the number of cells ( during the growth process)
2. Cell replacement // To replace dead and damaged
3. Regeneration // Production of new cells
4.  Asexual reproduction // the production of new individuals ( from parent organism )

Chapter 4.4 : Chemical Composition of Cells (ENzYmes)

Define an enzyme.

An enzymes is  an organic catalyst that accelerates the rate of a

biochemical reaction. It is made up of protein.

Explain why enzymes are needed in life processes

Every cell carries out thousands of biochemical reactions at the same time. Enzymes are biological catalysts that regulate almost all the cellular reactions. Enzymes are biological catalysts that speed up biochemical reactions in the cells.

List the general *Characteristic of enzymes

 - enzyme has an active site.

- which has a specific shape.

- active site is rigid.

- the shape is complementary to the shape of the substrate (as key fits into 

  a lock).

- forming an enzyme-substrate complex

- reaction takes place and the products are released.

- Enzymes work very rapidly

- Enzymes are not destroyed by the reactions which that catalyse

- Enzymes can work in either direction

- Enzymes are extremely specific

-  Enzymes are denatured by high temperature

-  Enzymes are sensitive to pH

*ReMinDer! -please refer the diagram

Figure 1 shows a biochemical reaction between an enzyme molecule and

            a substrate

• An enzyme has an active site which allows only specific substrate molecules to combine with it.
• The positioning of the substrate on the active site in the enzyme is accurate and precise, and is similar to a ‘lock and key’
• The substrate molecule (key) combines with the active site of the enzyme (lock) to form an unstable enzyme-substrate complex
• The product of the reaction is released from the active site of the enzyme.
• The enzyme can be reused

A temperature is a factor  that affect the activity of enzyme ; explain

- temperature increase, the rate of reaction increase.

- rate of reaction increases due to the increased kinetic energy of the

  substrate and enzyme molecules.

- these molecules move faster, colliding each other makes the rate of  

  reaction faster

- the increased rate of reaction would reach it limit when the optimum

  temperature is reached.

- this is the limit for the substrate and the enzyme to react optimally.

- temperature increased beyond /reach optimum temperature, the rate of

  reaction decrease.

- the bonds that holding the molecules break up

- causing the three dimensional shape of the enzyme molecule to be

   altered.

- the active site of the enzyme will no longer fit the subtrate.

- the enzyme is denatured and the rate of reaction decreases.                                                                                                                       

6.5 Assimilation of digested food in the liver and body cell.

Able to explain the assimilation of digested food ie. glucose , amino acids and lipids

Glucose

P1 : Excess glucose in the blood is converted to glycogen and

        stored in the liver

P2 :  When glucose level in the blood is low, glycogen is

        converted to glucose in the liver

P3 : Excess glucose is converted to lipids by the liver

P4 : In the body cells , glucose is oxidized to release energy in 

       cellular respiration

Amino acids

P5 : Amino acids is used to synthesise protein in the liver.

P6 : Excess amino acids undergo deamination  to

        produce urea in the liver.

P7 : Urea is then eliminated by the kidney  

P8 : Amino acid is used to synthesise enzymes /antibodies /

        hormones/new protoplasm/ repair damaged tissues

        in body cells  

Lipids

P9 : Excess lipids is stored in adipose tissues

P10 : Phospholipids and cholesterol make up the plasma membrane.                                                                              

Chapter 6 : Nutrition

Able to state whether the menu is a balanced diet and explain

The menu is not a balanced diet if :

The menu does not contain the 7 classes of food in the appropriate ratio.

        

Able to explain the consequences when taking the menu daily

(the menu is highly rich in carbohydrates and fats ,no vegetables and lack of vitamins
  and higher energy intake compared to energy requirements for a long time towards her health.

F1 : Constipation

E1 :  Her menu lacks fiber/roughage so her faeces moves too

         slowly through the colon

F2: Scurvy

E2 : lack of vitamin C  //any other vitamins deficiency with

        explanation

F3 : Obesity

E3 :  High intake of roasted chicken/ grilled beef/chocolate /

         chips increase the amount of fat stored in the body .

F4 : Diabetes mellitus

 E4 : excess of carbohydrate in rice/ chips/ potatoes increase the amount of glucose in blood when digested

F5 : Arteriosclerosis

E5 :  Roasted chicken/ grilled beef/ chocolate / chips contain

         fats which are deposited in the (lumen of ) blood vessels.

F6 : Heart attack

E6 : Roasted chicken/ grilled beef/chocolate / chips contain

        fats which are deposited in the coronary artery //cause

        blockage in the coronary artery.

7.3 Gaseous Exchange across the Respiratory Surfaces

Able to explain in detail the process of gaseous exchange at alveolus

-       The partial pressure of oxygen in the air of alveoli is higher compared to the partial pressure of oxygen in the blood capillaries

-       Therefore, oxygen diffuses across the surface of the alveolus and blood capillaries.

-       Then oxygen will combine with haemoglobin to form oxyhaemoglobin 

-       Lastly this form will be transported to all parts of the body.