GED Science Preparation Course：Life science: the human body, health and cells

1. 第1题，共17题

   Which list shows the levels of organization from smallest to largest?

   • AOrgan, tissue, cell, organ system, organism
   • BCell, organ, tissue, organism, organ system
   • CTissue, cell, organ, organism, organ system
   • DCell, tissue, organ, organ system, organism
   显示答案

   答案: D. Cell, tissue, organ, organ system, organism

   Cells form tissues, tissues form organs, organs form organ systems, and organ systems make up the organism.

2. 第2题，共17题

   Which cell part holds the DNA and controls the cell?

   • ACell membrane
   • BMitochondrion
   • CRibosome
   • DNucleus
   显示答案

   答案: D. Nucleus

   The nucleus holds the cell's DNA and directs its activities.

3. 第3题，共17题

   Which cell part releases energy from food through cellular respiration?

   • ACell wall
   • BNucleus
   • CChloroplasts
   • DMitochondria
   显示答案

   答案: D. Mitochondria

   Mitochondria carry out cellular respiration, releasing energy from glucose.

4. 第4题，共17题

   A scientist sees a cell with a cell wall and chloroplasts. What kind of cell is it most likely from?

   • AA plant
   • BA human
   • CA mosquito
   • DA dog
   显示答案

   答案: A. A plant

   Cell walls and chloroplasts are found in plant cells but not in animal cells such as those of dogs, humans and mosquitoes.

5. 第5题，共17题

   Which statement is part of cell theory?

   • AOnly animals are made of cells
   • BCells form from nonliving matter every day
   • CNew cells come from existing cells
   • DOrgans are the basic unit of life
   显示答案

   答案: C. New cells come from existing cells

   Cell theory says all living things are made of cells, the cell is the basic unit of life, and new cells come from existing cells.

6. 第6题，共17题

   What does mitosis produce?

   • AOne cell with double the DNA
   • BSex cells with half the chromosomes
   • CTwo identical cells
   • DEggs and sperm only
   显示答案

   答案: C. Two identical cells

   Mitosis makes two identical cells for growth and repair. Meiosis makes sex cells with half the chromosome number.

7. 第7题，共17题

   A human body cell has 46 chromosomes. How many chromosomes does a human egg cell have?

   • A92
   • B46
   • C12
   • D23
   显示答案

   答案: D. 23

   Meiosis halves the chromosome number, so sex cells have 46 ÷ 2 = 23 chromosomes.

8. 第8题，共17题

   During a run, your heart beats faster and you breathe faster. Why?

   • AYour bones need extra blood flow so they can grow during exercise
   • BYour kidneys must filter extra oxygen out of the blood
   • CMuscles need more oxygen, so the heart and lungs work harder
   • DYour digestive system must absorb food faster during a run
   显示答案

   答案: C. Muscles need more oxygen, so the heart and lungs work harder

   Body systems work together: the lungs take in more oxygen and the heart moves it faster to the working muscles.

9. 第9题，共17题

   What is homeostasis?

   • APassing traits from parents to their children
   • BKeeping conditions inside the body stable
   • CGrowing new cells by meiosis
   • DBreaking down food in the stomach
   显示答案

   答案: B. Keeping conditions inside the body stable

   Homeostasis keeps internal conditions such as temperature and blood sugar within a steady range.

10. 第10题，共17题

    You start shivering on a very cold day. What is this an example of?

    • ANegative feedback that keeps body temperature stable
    • BA chemical change in the skin caused by the cold air
    • CAn infection caused by a virus that lives in cold places
    • DPositive feedback that cools the body further
    显示答案

    答案: A. Negative feedback that keeps body temperature stable

    In negative feedback, a change triggers a response that reverses it. Shivering makes heat when the body gets too cold.

11. 第11题，共17题

    After a meal, blood sugar rises. Which hormone brings it back down?

    • AInsulin
    • BGlucose
    • CHemoglobin
    • DOxygen
    显示答案

    答案: A. Insulin

    The pancreas releases insulin, which lowers blood sugar. This is part of homeostasis.

12. 第12题，共17题

    Which nutrient is the body's main source of energy?

    • ACarbohydrates
    • BMinerals
    • CWater
    • DVitamins
    显示答案

    答案: A. Carbohydrates

    Carbohydrates are the main energy source. Vitamins, minerals and water do not supply Calories.

13. 第13题，共17题

    A snack has 12 grams of fat. Fat gives 9 Calories per gram. How many Calories come from fat?

    • A21 Calories
    • B48 Calories
    • C108 Calories
    • D120 Calories
    显示答案

    答案: C. 108 Calories

    12 g × 9 Calories per gram = 108 Calories. 48 would use 4 Calories per gram, which is for carbohydrate and protein.

14. 第14题，共17题

    Jordan's daily energy is shown in the table. If this continues, what is most likely to happen?

    	Calories per day
    Calories eaten	2,500
    Calories used	2,200

    • AJordan's weight cannot change because Calories are used up by digestion
    • BJordan uses stored fat to make up a 300-Calorie shortfall
    • CJordan loses weight because the body burns the extra 300 Calories off as heat
    • DJordan stores the extra 300 Calories a day, mostly as fat, and gains weight
    显示答案

    答案: D. Jordan stores the extra 300 Calories a day, mostly as fat, and gains weight

    Jordan takes in 2,500 − 2,200 = 300 more Calories than he uses each day. The body stores extra energy, mostly as fat.

15. 第15题，共17题

    How does a vaccine help prevent disease?

    • AIt kills all of the bacteria that live in the body, good and bad
    • BIt replaces old red blood cells with new ones
    • CIt trains the immune system to recognize a pathogen
    • DIt cures diseases that are caused by genes
    显示答案

    答案: C. It trains the immune system to recognize a pathogen

    A vaccine prepares the immune system so it can respond quickly to the real pathogen.

16. 第16题，共17题

    A doctor says a patient's illness is caused by a virus. Why would an antibiotic not help?

    • AAntibiotics only work on fungi
    • BViruses are too large for antibiotics
    • CAntibiotics kill bacteria but do not work on viruses
    • DAntibiotics only prevent disease spread by mosquitoes
    显示答案

    答案: C. Antibiotics kill bacteria but do not work on viruses

    Antibiotics act on bacteria. They have no effect on viruses.

17. 第17题，共17题

    Malaria spreads when mosquitoes bite people. In this case, what is the mosquito called?

    • AA vector
    • BA decomposer
    • CA producer
    • DA vaccine
    显示答案

    答案: A. A vector

    A vector is a living thing, such as a mosquito, that carries a pathogen from one host to another.

键盘：按1–4作答，按 Enter 进入下一题。

真实考试：145 on a 100–200 scale