HAPPY THANKSGIVING TO MY USA FANS!

We must not forget to give thanks to the Almighty, Supreme, and Infinite God, each day that we have the breath of life. If your heart beats 72 beats per minute automatically, if you can perform the basic functions of life, if you can see and hear, or even reason and think, you must be grateful to your maker and creator. As you eat your turkey and drink various drinks, take a moment to say a

PRAYER 

OF

THANKSGIVING 

TO 

THE ONE WHO CREATED YOU

 AND 

BROUGHT YOU INTO BEING.

HAPPY THANKSGIVING TO ALL MY FAITHFUL FANS 

AND 

FOLLOWERS IN THE USA!

THE DIVERSITY OF FISHES

VIDEO ANIMATION ON ACTION POTENTIAL

This is a video produced by one of my students as part of her class science project on action potential. Enjoy watching it!

SCIENCE TEST MODULE 1

ANSWERS TO SCIENCE MODULE 1

1.   If the hydrogen ion concentration of a solution is 1 x 10^-5. What is the pH of the solution?

A.    1

B.     10

C.     5

D.    2

2.   If the hydrogen ion concentration of a solution is 1 x 10^-3. What can you say about the solution?

A.     It is a weak acid

B.      It is a strong acid

C.      It is a weak base

D.     It is a strong base

3. A student placed a blue ink drop in a jar of water. After some time, the whole water turned blue.  

Which of the following processes occurred?

      A. Osmosis

      B. Simple Diffusion

      C. Active Diffusion

      D. Facilitated diffusion

4. Water enters the roots of plants by which of the following process?

     A. Osmosis

     B. Simple Diffusion

     C. Active Diffusion

     D. Facilitated diffusion

5. Oxygen from the atmosphere enters the blood from the lung by ____________________ .

    A. Osmosis

    B. Simple Diffusion

    C. Active Diffusion

    D. Facilitated diffusion

6. During the formation of sodium chloride (NaCl), sodium loses one electron from its outermost shell (valence shell) to chlorine. Which type of bond is formed between these two atoms?  

   A. Metallic bond

   B. Ionic bond

   C. Covalent bond

   D. hydrogen bond

7. When a red blood cell (RBC) is placed in a hypertonic solution, it will ____________________

   A. Increase in size

   B. Shrink

   C. Rupture

   D. Remain the same

8. How would cream crackers taste if it is chewed slowly?

    A. Sweet    

    B. Bitter    

    C. Sour      

    D. Tasteless

9. What will be the end-product of sucrose digestion?

    A. glucose    

    B. glucose and galactose  

    C. galactose and fructose    

    D. glucose and fructose

10. Which of the following will turn blue-black when tested with Lugol's solution?

    A. protein  

    B. starch    

    C. glucose    

    D. fructose

TYPES OF NATURAL SELECTION

In the previous blog, I explained what natural selection is about. Today, I will delve into the different ways in which it is classified.

SELECTION BASED EFFECT ON A TRAIT

1. Stabilizing selection: This acts in such a way that the trait is held at a stable optimum. For example, tall plants in a forest are susceptible to being blow down by the wind; short plants are susceptible to competition for sunlight; so that compromise leads to the development of medium height plants.

2. Directional selection: This acts during transitional periods when the current mode of the trait is sub-optimal, and alters the trait towards a single new optimum. For example, the shortage of food at ground level made it difficult for the giraffe with short necks to survive. The development of long necks

3. Disruptive selection: This acts during transitional periods when the current mode is sub-optimal, but alters the trait in more than one direction. Example: If there are three types of plants in an area, tall, medium, and short, that are pollinated by three individuals. If the pollinator of the medium plant is no more there, the medium plant's population will decrease while that of the short and tall will remain. 

SELECTION BASED ON EFFECT ON ALLELE FREQUENCY

1. Positive selection: This effect leads to an increase frequency of an allele.

2. Negative selection: This effect leads to a decrease in the frequency of an allele.

SELECTION BASED ON EFFECT ON GENETIC DIVERSITY

1. Purifying selection: This acts to remove the genetic variation in a population.

2. Balancing selection: This acts to maintain the genetic variation in a population.

THEORIES OF EVOLUTION

Charles Robert Darwin was one of the founders of evolution. Other people who contributed to this were Jean-Baptiste Lamarck and Alfred Russel Wallace.

• Darwin Theory or Darwinism: This states that all species of organisms arise and develop through the natural selection of small, inherited variations (traits) that increase the individual's ability to compete, survive, and reproduce.

• Thomas Henry Huxley, for the purpose of economics, coined the word Darwinism in April 1860, in which he used it to illustrate the survival of the fittest in economic terms.

• Jean-Baptiste Lamarck was associated with the theory of inheritance of acquired characteristics (soft inheritance). He proposed the "Use and disuse of characteristics."

• Natural selection was coined by Alfred Russel Wallace and popularized jointly by Darwin in their joint publication in 1858.

• Natural selection is the process by which animals and plants with traits considered desirable by them are systematically favored for reproduction. 

• Survival of the fittest is central to natural selection. Individuals that are more fit have a better chance or potential for survival.

Examples of natural selection:

• The sickle cell anemias have  low fitness potential in the general population but the trait confers immunity to malaria. So in areas where malaria infection rates are high, it has a high fitness value in that population. 
• Finches of the Galapagos Islands differ in the shapes of their beaks. The beaks of over 13 species is suited to its preferred food, suggesting that the beak shapes evolved by natural selection.

Natural selection can act on any inheritable phenotypic traits. The selection pressure can come from any aspects of the environment. This include sexual selection where the female organism chooses which male it prefers to mate with, or competition with same or other species for food or space.

There are different types of natural selection which I will discuss in the next post. Stay tuned!