GED Science Preparation Course：Life science: ecosystems, heredity and evolution

1. 第1题，共16题

   In an ecosystem, what does a producer do?

   • AMakes its own food using light energy
   • BBreaks down dead matter
   • CLives inside another organism and harms it
   • DEats only other animals
   显示答案

   答案: A. Makes its own food using light energy

   Producers such as plants make food by photosynthesis, using light energy.

2. 第2题，共16题

   What is the role of decomposers such as fungi and bacteria?

   • AThey break down dead matter and recycle nutrients
   • BThey carry pathogens from one host animal to another
   • CThey hunt and eat herbivores in the food chain
   • DThey make their own food from sunlight
   显示答案

   答案: A. They break down dead matter and recycle nutrients

   Decomposers recycle matter by breaking down dead organisms and wastes.

3. 第3题，共16题

   In the food chain grass → grasshopper → frog → hawk, what do the arrows show?

   • AWhich way each animal moves when it hunts
   • BThe order in which the animals appeared on Earth
   • CThe direction energy flows, from food to eater
   • DWhich animal in the chain is the largest
   显示答案

   答案: C. The direction energy flows, from food to eater

   Each arrow points from the organism that is eaten to the organism that eats it.

4. 第4题，共16题

   In the food chain grass → grasshopper → frog → hawk, which organism is a herbivore?

   • AFrog
   • BGrasshopper
   • CGrass
   • DHawk
   显示答案

   答案: B. Grasshopper

   A herbivore eats plants. The grasshopper eats grass; the frog and hawk eat animals.

5. 第5题，共16题

   Producers in an ecosystem store 20,000 kJ of energy. Using the 10% rule, about how much reaches the secondary consumers?

   • A20 kJ
   • B18,000 kJ
   • C200 kJ
   • D2,000 kJ
   显示答案

   答案: C. 200 kJ

   About 10% passes up each level: 20,000 → 2,000 kJ (primary consumers) → 200 kJ (secondary consumers).

6. 第6题，共16题

   Deer were brought to an island in year 1. Based on the table, what is the island's carrying capacity for deer?

   年份	Deer on the island
   1	40
   3	120
   5	260
   7	310
   9	305
   11	312

   • AAbout 40 deer
   • BAbout 310 deer
   • CAbout 120 deer
   • DAbout 620 deer
   显示答案

   答案: B. About 310 deer

   Carrying capacity is the largest population the environment can support over time. The count levels off near 310.

7. 第7题，共16题

   Bees get nectar from flowers, and the flowers get pollen carried to other flowers. What kind of relationship is this?

   • APredator and prey
   • BParasitism
   • CMutualism
   • DCompetition
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   答案: C. Mutualism

   In mutualism, both species benefit.

8. 第8题，共16题

   A tick feeds on a dog's blood and can make the dog sick. What kind of relationship is this?

   • AParasitism
   • BMutualism
   • CDecomposition
   • DCommensalism
   显示答案

   答案: A. Parasitism

   In parasitism, one organism benefits and the other is harmed.

9. 第9题，共16题

   A new snake species with no natural predators is released on an island. What is the most likely effect?

   • APopulations of the animals it eats may crash
   • BThe snake will become a producer
   • CThe island's plants will stop photosynthesis
   • DNothing will change because snakes are small
   显示答案

   答案: A. Populations of the animals it eats may crash

   An invasive species can disrupt an ecosystem, causing the populations it preys on to decline or even go extinct.

10. 第10题，共16题

    A pea plant has the gene pair Tt and is tall. Which describes "Tt" and "tall"?

    • ATt is the genotype; tall is the phenotype
    • BTt is the phenotype; tall is the genotype
    • CBoth are phenotypes
    • DBoth are genotypes
    显示答案

    答案: A. Tt is the genotype; tall is the phenotype

    The genotype is the pair of alleles. The phenotype is the trait you can see.

11. 第11题，共16题

    Two parents both have the genotype Aa. The recessive trait shows only in aa. What is the chance a child shows the recessive trait?

    • A0%
    • B25%
    • C50%
    • D75%
    显示答案

    答案: B. 25%

    A Punnett square for Aa × Aa gives AA, Aa, Aa and aa. Only 1 of 4 boxes is aa, so the chance is 25%.

12. 第12题，共16题

    One parent is Aa and the other is aa. What is the chance a child has the genotype aa?

    • A25%
    • B100%
    • C50%
    • D75%
    显示答案

    答案: C. 50%

    Aa × aa gives Aa, Aa, aa and aa. Two of four boxes are aa, so the chance is 50%.

13. 第13题，共16题

    A mutation happens in a skin cell on a woman's arm. Can it be passed to her children?

    • ANo, only mutations in sex cells are inherited
    • BYes, but only to her sons and never to her daughters
    • CNo, because mutations never change any DNA
    • DYes, all mutations are passed to children
    显示答案

    答案: A. No, only mutations in sex cells are inherited

    Only mutations in sex cells (eggs or sperm) can be inherited by offspring.

14. 第14题，共16题

    A farmer sprays the same insect poison for many years, and it slowly stops working. What is the best explanation?

    • ASurvivors reproduced, so resistance became more common
    • BEvery insect became resistant during its own lifetime
    • CThe poison turned into food for the insects
    • DThe insects chose to change their own DNA so they could survive
    显示答案

    答案: A. Survivors reproduced, so resistance became more common

    This is natural selection: individuals with a helpful inherited trait survive and reproduce more, so the trait spreads over generations.

15. 第15题，共16题

    On a cladogram, species B and C split from each other more recently than either split from species A. What does this show?

    • AA, B and C are all equally related to each other
    • BA is the newest species of the three
    • CB and C are more closely related to each other
    • DB and C cannot share any common ancestor
    显示答案

    答案: C. B and C are more closely related to each other

    In a cladogram, species that branch apart more recently share a more recent common ancestor, so they are more closely related.

16. 第16题，共16题

    Two groups of one squirrel species are separated by a canyon for a very long time. They change until they can no longer breed together. What has happened?

    • ASpeciation
    • BHomeostasis
    • CMitosis
    • DPhotosynthesis
    显示答案

    答案: A. Speciation

    Speciation is the forming of a new species when separated groups change until they can no longer interbreed.

键盘：按1–4作答，按 Enter 进入下一题。

真实考试：145 on a 100–200 scale