Esta série está disponível no idioma original.

1. Tema: Cell biology

   1. Which organelle is the site of aerobic respiration?

   AMitochondrionBRibosomeCChloroplastDGolgi body
   Solução

   A. Mitochondrion

   • Aerobic respiration releases energy from glucose using oxygen.
   • Its later stages take place in the mitochondria, which make most of the cell's ATP.

2. Tema: Living things

   2. Which of these is NOT a characteristic of living things?

   AExcretionBIrritabilityCReproductionDCrystallisation
   Solução

   D. Crystallisation

   • Living things show movement, respiration, nutrition, irritability, growth, excretion and reproduction.
   • Crystallisation happens in non-living substances such as salt.

3. Tema: Classification

   3. To which kingdom do mushrooms belong?

   APlantaeBMoneraCFungiDProtista
   Solução

   C. Fungi

   • Mushrooms have no chlorophyll and feed by absorbing nutrients from dead matter.
   • They have cell walls of chitin, which places them in the kingdom Fungi.

4. Tema: Plant transport

   4. What is the main function of the xylem?

   ATransport of manufactured foodBTransport of water and mineral saltsCGas exchangeDStorage of starch
   Solução

   B. Transport of water and mineral salts

   • Xylem carries water and dissolved mineral salts from the roots to the leaves.
   • Phloem, not xylem, carries manufactured food.

5. Tema: Digestion

   5. Which enzyme starts the digestion of starch in the mouth?

   ASalivary amylase (ptyalin)BPepsinCLipaseDTrypsin
   Solução

   A. Salivary amylase (ptyalin)

   • Saliva contains amylase, also called ptyalin.
   • It breaks starch down into maltose.

6. Tema: Circulation

   6. Which blood vessel carries oxygenated blood from the lungs to the heart?

   APulmonary arteryBAortaCVena cavaDPulmonary vein
   Solução

   D. Pulmonary vein

   • Veins carry blood to the heart.
   • The pulmonary vein is the one vein that carries oxygenated blood, from the lungs to the left atrium.

7. Tema: Excretion

   7. What is the functional unit of the kidney?

   ANeuronBAlveolusCNephronDVillus
   Solução

   C. Nephron

   • Each kidney contains about a million nephrons.
   • Nephrons filter the blood and form urine.

8. Tema: Hormones

   8. Which hormone lowers the level of glucose in the blood?

   AGlucagonBInsulinCAdrenalineDThyroxine
   Solução

   B. Insulin

   • Insulin is made by the pancreas (islets of Langerhans).
   • It makes the liver and muscles take up glucose and store it as glycogen.

9. Tema: Genetics

   9. Two tall plants, both Tt, are crossed. Tall (T) is dominant over short (t). What fraction of the offspring is expected to be tall?

   A3/4B1/2C1/4DAll of them
   Solução

   A. 3/4

   • Tt × Tt gives TT, Tt, Tt and tt.
   • TT and Tt are tall, so 3 out of 4 are tall.

10. Tema: Blood groups

    10. Which ABO blood group is known as the universal donor?

    AABBACBDO
    Solução

    D. O

    • Group O red cells carry neither A nor B antigens.
    • They are not attacked by the antibodies of other groups, so O can be given to all groups in the ABO system.

11. Tema: Ecology

    11. In the food chain grass → grasshopper → lizard → hawk, which organism is the secondary consumer?

    AGrasshopperBHawkCLizardDGrass
    Solução

    C. Lizard

    • Grass is the producer and the grasshopper, which eats it, is the primary consumer.
    • The lizard eats the primary consumer, so it is the secondary consumer.

12. Tema: Nitrogen cycle

    12. Which bacterium fixes nitrogen in the root nodules of legumes?

    ANitrosomonasBRhizobiumCNitrobacterDPseudomonas
    Solução

    B. Rhizobium

    • Rhizobium lives in the root nodules of beans, groundnuts and other legumes.
    • It turns nitrogen gas into compounds the plant can use.

13. Tema: Disease vectors

    13. Which organism transmits the malaria parasite to humans?

    AFemale Anopheles mosquitoBMale Anopheles mosquitoCFemale Culex mosquitoDTsetse fly
    Solução

    A. Female Anopheles mosquito

    • Malaria is caused by Plasmodium.
    • Only the female Anopheles mosquito feeds on blood and passes the parasite on.

14. Tema: Photosynthesis

    14. What are the products of photosynthesis?

    ACarbon(IV) oxide and waterBGlucose and carbon(IV) oxideCStarch and waterDGlucose and oxygen
    Solução

    D. Glucose and oxygen

    • 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ in the presence of light and chlorophyll.
    • The products are glucose and oxygen.

15. Tema: Nervous system

    15. Which part of the brain controls balance and coordination of movement?

    ACerebrumBMedulla oblongataCCerebellumDHypothalamus
    Solução

    C. Cerebellum

    • The cerebellum coordinates muscle movements and keeps the body balanced.
    • The medulla controls breathing and heart rate; the cerebrum controls thought and voluntary actions.