Latest Biological Science Reviewer 9 - LET EXAM - Questions & Answers

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Latest Biological Science Reviewer 9


no1. What does a niche include?

I. interaction with the environment
II. Habitat
III. Place in the food chain

A. I, II and III
B. I and II
C. I and III
D. II and III

Ans: A. I, II and III
- An ecological niche is the role and position a species has its environmental when lives; how it meets for food and shelter, how it survives, and how it reproduces. A species’ niche all of its interaction with the biotic and abiotic factors of environment.

2. What happens when two organism occupy the same ecological niche?

A. Both organism will die
B. It will result to mutualism
C. Competition will never be  intensive
D. They will connive to widen their habitat

Ans: C. Competition will never be  intensive
- According to the competitive exclusion principle, no two species can occupy the same ecological niche. The two species will compete for the limited resources that they both need. They inevitably compete for the dominance of this niche until one of them brings about the extinction of the other.

3. In which biome can you see animals that burrow or seek shelter during the day become active at night?

A. Deciduous forest
B. Desert
C. Savanna
D. Taiga

Ans: B. Desert
- The biological processes of animal tissue can function only within narrow temperature. When this range. When this range is exceed , the animals dies. Due to extreme temperature in the dessert, many animals (especially mammals and reptiles) are  crepuscular that is they are active only at dusk and again at dawn. Many animals are completely nocturnal restricting all their activities to the cooler temperature of the night. Bats many snakes, most rodents and some larger mammals like foxes and shrunk, are nocturnal, sleeping  in a cool den, cave or burrow by day. Some smaller deserts animals burrow below the surface of the soil or sand to escape the high temperature at the desserts surface. These include many mammals, reptiles insects and all desert amphibians. Rodents may be plug the entrance to their burrows to keep out hot, desiccating air.

4. Which biome is the coolest?

A. Temperature coniferous forest
B. Temperature grassland
C. Tropical rainforest
D. Tundra

Ans: D. Tundra
- The tundra is the coldest and the driest of all biomes on Earth. Temperature ventures above freezing for moments each year. The tundra covers about one fifth of the land on earth. The word of tundra comes from a Finnish words that means treeless plain, which is a circle that surrounds the north pole.

5. Why is the Philippines classified as a tropical rainforest?

I. located close to the equator
II. Surrounded by vast oceans
III. Rich in second growth forest
IV. Receivesa high rainfall

A. I and IV
B. II and IV
C. I, II and III
D. I, II and IV


Ans: D. I, II and IV
- Tropical rainforest are defined by the fact they warm wet year-rounded just like the Philippines. Tropical rainforest are found in the world’s hottest and wettest areas. Namely those closest to the equator. They receive a high rainfall. The combination of lots of moisture and consistent year-round warm weather makes tropical rainforest particularly lush areas of plant life.

6. What is being shown in the renewal of a forest after a fire?

A. Autogenic succession
B. Allogenic succession
C. Primary succession
D. Secondary succession

Ans: D. Secondary succession
- There are two different types of succession: primary succession occurs in essentially lifeless regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. Secondary succession refers to the concept of an ecosystem reviving itself after all or a portion has been destroyed. The renewal of a forest after a fire: Th fire itself destroy a majority of different types of trees and plant life. Because seeds and roots and other plants and tree parts remain in and on the soil, gradually the plants and trees begin to grow again and eventually return to the state of the original ecosystem.

7. What is the initial establishment of a plant community in a new area?

A. Aggregation
B. Ecesis
C. Invasion
D. Nudation

Ans: B. Ecesis
- Ecesis is the initial establishment of plan community. It also known as colorization. In this stage, the early colonizing species proliferate abundantly through germination growth and reproduction. Aggregation is the increase in a population of the species which has become established in the area. Nudation is the development of a bare site uninhabited by any organisms. The process of invasion helps the arrival of seeds spore from establishment of species.

8. Which of the following is an example of primary succession?

A. A barrel land
B. Formation of new island
C. Evolution of a new animal species
D. Renewal of a crop after harvesting

Ans: B. Formation of new island
- Primary succession is a charge in vegetation which occurs on previously unvegetated terrain. Examples of where primary succession may take place include the formation of new islands, on new volcanic rock, and on land formed glacial retreats.

9. Development that meets the needs of the present without comprising the ability of future generations to meet their own needs aptly describes ________.
A. ecological development
B. environment integrity
C. environmental potential
D. sustainable development

Ans: D. sustainable development
- Sustainable development is development that needs of present without compromising the ability of future generations to meet their own needs. The definition of sustainability may taken further and it is widely accepted that to achieve sustainability we must balance economic, environmental and social factors in equal harmony. This implies that we need to look after our planet, our resources and our people to ensure that we can live in a sustainable manner and that we can hand down our planet to our children and our grandchildren to live true sustainability.


10. Which of the following environmental conditions been blamed for the usual occurrence of fish skills in our lakes?

A. Acid rain
B. Atmospheric pollution
C. Euthrophication
D. Silting of lakes

Ans: C. Euthrophication
- Eutrophication is the excessive richness of nutrients in a lake or other body of water frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life just like fish kill from lack of oxygen.

11. Which of the following factors are facts about carbon?

I. It can exist in amorphous state.
II. It forms strong ionic bonds with a variety of elements
III. It has a unique ability to bond to itself in long chains
IV. It has a very low its melting point and sublimation point

A. I and II
B. I and III
C. II and III
D. I, III, and IV

Ans: B. I and III
- Carbon can exist in amorphous state. It means it lacks crystalline structure or a distinct shape. It has the special ability to bond to itself in long chains. The greater the number of carbons atoms in a molecule the more ways there are to connect these atoms in different arrangements. Carbon forms a strong covalent bonds with a variety of elements like hydrogen, nitrogen, oxygen and the halogens. Carbon has the highest melting/sublimation point of all elements and, in the other form of diamond has the highest thermal conducting of any element.
12. Carbon can exist with several different structures and so its atoms area arranged different. What is this unique property of carbon?

A. Allotropy
B. Implementrabilty
C. Viscosity
D. Volatility

Ans: A. Allotropy
- Allotrophy is the property of carbon to exist in two or more different forms, in the same physical state, known as allostropes. Carbon is capable of forming many allotropes due to its valency. The common crystalline allotrophes area graphite, diamond and fullerenes  impenetrability is the quality of matter whereby two bodies cannot occupy the same space at the same time. Viscosity is the resistance to flow. Volatility is the abilty to evaporate easily.

13. Which carbon is used as pigment in black ink/s?

A. Carbon black
B. Charcoal
C. Coke
D. Graphite

Ans: A. Carbon black
- Carbon black is formed when hydrocarbons such as methane are heated in the presence of very little amount of oxygen. It is used as the black pigment in printing ink. Charcoal is formed when wood is heated intense in the absence of air. Activated charcoal is commonly used in filters to remove undesirable odors. Coke is a good reducing agent in metallurgical processes. Graphite is used for pencil tips, high temperature crucibles, dry cells, electrodes and as lubricant.

14. Water can be described as an amphoteric molecule. What does this mean?

A. It is tasteless and odorless
B. It can react both as acid or base
C. it can exist as solid, liquid or gas
D. It can dissolves many substance found in nature

Ans: B. It can react both as acid or base
- The prefix of the word “amphoteric” is derived from a Greek prefix amphi-, which means both. An amphoteric substance is a substance that has ability to act either as an acid or a base.

15. What is the state of matter of water at 25 degrees Celsius?

A. Gas
B. Liquid
C. Plasma
D. Solid

Ans: B.
- Water exist in the liquid, solid and gaseous states. It is in dynamic equilibrium between the liquid and gas states at 0 degrees Celsius and 1 atm pressure. At room  temperature (approximately 25 degree Celsius), it is a tasteless, odorless and colorless liquid.

16. Water is a polar molecule. What does this mean?

A. Water is a molecule with no charge
B. It has identical charges at opposites ends
C. It has opposites charges at opposites ends
D. It has unequal number of protons and electrons

Ans: C. It has opposites charges at opposites ends
- Because oxygen has a higher electronegativity than hydrogen, water has a partial negative charge near the oxygen due to the unshared pair of electrons and partial positive charges near the hydrogen atoms. This charge difference causes water molecules to be attracted to each other (the relatively positive areas are attracted to the relatively negative areas) as well as o other polar molecules to dissolve in water is due polarity.

17. Which formula represents a saturated hydrocarbon?

A.C₂H₂
B. C₂H₄
C. C₃H₆
D. C₃H₈

Ans: D. C₃H₈
- Hydrocarbons in which all the carbon-carbon bonds area called alkanes. Alkanes are saturated by hydrocarbons. This means that they contain only carbon and hydrogen atoms bonded by single bonds only. The general formula for an alkane is Cn H₂n̟₂. In this this formula, n is the number of carbons atom n in the molecule for example there are 3 carbon atoms then the number of hydrogen atoms shall be 2(3) = 6+2 = 8.

18. Among the members of the alkane family, which is similar?

A. Condensed formula
B. General formula
C. Molecular formula
D. Structural formula

Ans: B. General formula
- The general formula for all alkanes is Cn H₂n+2. The molecular formula is the actual ratio of atoms to one another in a molecule. Propane and butane are members of the alkane  family. However they differ in molecular formula. Propane is C₃ H₈ while butane is C₄ H₁₀ atoms. A condensed formula is a simplification of the structural formula. The condensed formula of propane is CH₃CH₂CH₃ while butane CH₃CH₂CH₂CH₃

19. Which of the following is an organic compound?

A. Lime (CaO)
B. Methane (CH₄)
C. Salt (NaCI)
D. Sulfuric acid (H₂SO₄)

Ans: B. Methane (CH₄)
- Usually, organic compounds contain carbon. Among all the choices only members contain carbon. However there are also carbon containing inorganic compounds like carbon monoxide and carbon dioxide because they possess properties that are similar to inorganic compounds.

20. A liquid is dissolve in water and was found out to have a general  formula of R-OH. What could be the name of the liquid?

A. Methane
B. Methanol
C. Mechanic acid
D. Methyl methanoate

Ans: B. Methanol
- Alchohol contain the hydroxyl (OH) as the functional group and are considered derivates of water. The OH bond is polar, so alcohols are soluble in polar solvents like water. Simple alchohol are named by changing the last letter in the name of the corresponding hydrocarbon to – ol. For instance, methane becomes methanol.

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