Science - 1 to 13 (GR.9)

What are micro-organisms?

Organisms too small to be seen clearly with the naked eye; unicellular or multicellular.

List the main groups of micro-organisms.

"Bacteria

Where do micro-organisms live?

In soil, ice glaziers, deserts and other extreme environments

Are most micro-organisms favourable or harmful?

Most are favourable but some are harmful.

Name two unicellular algae mentioned.

Chlamydomonas and diatoms.

What are phytoplanktons?

Microscopic algae floating on water surfaces.

Give an example of a filamentous alga.

Spirogyra.

What is a substrate in microbiology?

"Material or surface where microbes grow (e.g.

What is food spoilage?

Change in food due to microbial activity making it unfit to eat.

Name three types of food spoilage processes.

"Fermentation, putrefaction and rancidity

Give an example of a bacterial plant disease.

Bacterial wilt.

Give two fungal plant diseases mentioned.

Powdery mildew and late blight.

Which microorganism is used in yoghurt production?

Lactobacillus bulgaricus (and Streptococcus thermophilus).

Why is milk heated before making yoghurt?

To kill undesirable microbes and denature proteins for proper fermentation.

What gas is the main component of biogas?

Methane.

Name an application of microbes in industry.

"Production of alcohol

What is bio-remediation?

Using microbes to remove pollutants from the environment.

What is bio-leaching?

Using microbes to extract metals from low-grade ores.

Which bacteria fix atmospheric nitrogen in legumes?

Rhizobium.

What is an antibiotic?

A substance produced by microbes that inhibits or kills bacteria.

Give an example of a fungus that produces antibiotics.

Penicillium (penicillin).

What role do microbes play in composting?

They decompose organic matter into nutrient-rich compost.

Name a microbe used as a bio-pesticide.

Bacillus thuringiensis (Bt).

Why shouldn't antibiotics be used for viral infections?

"Antibiotics target bacteria

What is pasteurization?

Heating food to kill harmful microbes and reduce spoilage.

What is fermentation used for industrially?

"Producing ethanol

Give one harmful effect of microbes.

"Cause human

How do microbes help in waste treatment?

They decompose organic waste and remove pollutants.

What are extremophiles?

"Micro-organisms that live in extreme environments (hot springs

Why are microbes widely used in industry?

"Fast growth

What is a vaccine in microbial context?

Preparation using weakened/killed microbes or parts to induce immunity.

Name an example of microbial spoilage of crops.

Late blight of potato caused by fungus-like organism.

How are vinegar-producing microbes classified?

Acetobacter (bacteria) convert ethanol into acetic acid.

What is a biofertilizer?

Product containing living microbes that enrich soil nutrients.

What is the sensory organ for vision?

The eye.

On which part of the eye is an image formed?

Retina.

Name the transparent front layer of the eye.

Cornea.

What is the iris?

Muscular ring controlling pupil size and light entry.

What is the pupil?

The opening in the centre of the iris that admits light.

What type of lens is the eye lens?

A converging (convex) lens.

What is the function of the lens?

Focus light onto the retina for clear images.

What fluid maintains eyeball shape behind the lens?

Vitreous humour.

Where are rods and cones located?

On the retina.

What is the fovea (yellow spot)?

Area of sharpest vision on the retina.

What is the blind spot?

Area on retina where optic nerve exits; no photoreceptors.

How is long sight (hypermetropia) corrected?

With a convex (converging) lens.

How is short sight (myopia) corrected?

With a concave (diverging) lens.

What is a cataract?

Clouding of the lens causing blurred vision.

What is glaucoma?

Eye disease often from high intraocular pressure damaging optic nerve.

Give two precautions to protect eyes.

Avoid looking at sun directly; wear safety goggles during welding.

Which part of the ear vibrates with sound waves?

Tympanic membrane (eardrum).

Name the three ossicles.

"Malleus

What structure converts vibrations into nerve impulses?

Cochlea.

Which ear structure helps balance?

Semi-circular canals.

What is the audible frequency range for humans?

"Approximately 20 Hz to 20

What is the function of the Eustachian tube?

Equalize pressure between middle ear and throat.

What causes 'sore eyes' (conjunctivitis) often?

"Viral infection

What is tinnitus?

Ringing or buzzing in the ear not from external sound.

What are cones responsible for?

Colour vision.

What are rods responsible for?

Low-light (scotopic) vision and peripheral vision.

What is presbyopia?

Age-related difficulty focusing on close objects.

Why avoid inserting objects into the ear?

"Risk of damage

How does the ear transmit sound to the brain?

Vibrations→tympanic membrane→ossicles→cochlea→auditory nerve→brain.

What is a common remedy for impaired hearing?

Hearing aids for some types of hearing loss.

What is reverberation?

Prolonged persistence of sound in a space due to multiple reflections.

Why reduce exposure to loud noises?

To prevent hearing damage and deafness.

What is accommodation in the eye?

Changing lens curvature to focus at different distances.

What is matter?

Anything that has mass and occupies space.

What are elements?

Pure substances consisting of one type of atom.

What is a compound?

Substance formed from two or more elements chemically bonded.

What is a mixture?

Combination of substances not chemically bonded.

What is homogeneous mixture?

Mixture with uniform composition throughout.

What is heterogeneous mixture?

Mixture with non-uniform composition.

What is atomic number?

Number of protons in an atom's nucleus.

What is mass number?

Total number of protons and neutrons in the nucleus.

Define proton.

Positively charged particle in the nucleus.

Define electron.

Negatively charged particle orbiting the nucleus.

Define neutron.

Neutral particle in the nucleus.

What is a molecule?

Two or more atoms chemically bonded.

What is a pure substance?

A material with constant composition and properties.

Give an example of a pure element.

Oxygen (O₂) or iron (Fe).

Give an example of a compound.

Water (H₂O) or sodium chloride (NaCl).

What is a chemical symbol?

One- or two-letter abbreviation for an element.

What is a chemical formula?

Representation of a compound showing element types and ratios.

What is a physical change?

Change affecting form but not chemical composition.

What is a chemical change?

Change that produces new substances with different properties.

What is conservation of mass?

Mass is neither created nor destroyed in chemical reactions.

What is a mixture separation technique?

"Filtration

What is distillation used for?

Separating liquids with different boiling points.

What is chromatography used for?

Separating components of mixtures based on mobility.

What is an alloy?

Mixture of metals or metals with other elements.

What is a solvent?

Substance that dissolves a solute to form a solution.

What is solubility?

Maximum amount of solute soluble in a given amount of solvent.

How is density defined?

Mass per unit volume (ρ = m/V).

What is a hydrometer used for?

Measuring density/specific gravity of liquids.

What is a homogeneous solution example?

Salt dissolved fully in water.

What is an ionic compound characteristic?

Conduct electricity when molten or dissolved.

What is a covalent compound characteristic?

Generally do not conduct electricity; share electrons.

What is a mixture vs compound difference?

Mixtures are physically combined; compounds chemically combined.

What is particle theory of matter simple idea?

Matter made of tiny particles in constant motion.