The mountain · Science ridge · camp 3 of 4

Biology

Biology: cells, body systems, ecosystems, genetics and evolution, and the experiments that showed how each of them was found out.

Eight rungs, one trail

Every camp on the mountain has the same eight rungs: the eight altitudes Alpenrise measures, read back in the words of your own school system. Rung 1 is the bottom of secondary school; rung 8 is beyond the final exam.

One question from each rung

The mountain draws three questions per rung from the same slice as the free placement. Here is one from each rung of Biology, shown without its answer.

1. Rung 1 · Explorer · Year 7A butterfly spends 4 days as an egg, 25 days as a caterpillar and 7 days as a pupa before the adult comes out. How many days is that altogether?
2. Rung 2 · Pathfinder · Year 8A seed bank stores crop seeds in freezers so that farmers hundreds of years from now still have them. Because stored seeds slowly lose the ability to grow, a sample from each batch is sown and checked every few years. An earlier test showed that 84% of the seeds in a batch still germinate. Determine how many of 350 seeds from that batch are expected to come up.
3. Rung 3 · Voyager · Year 9In the word equation for photosynthesis, light energy and chlorophyll are written above the arrow because they are needed but are not used up. Complete the equation: carbon dioxide + water → ______ + oxygenglucose · oxygen · starch · light
4. Rung 4 · Navigator · Year 10A water molecule travels from the soil, into a root, up the plant and out into the air. State the correct order of the parts it passes through on the way.root hair cell → root cortex → xylem vessel → mesophyll cell → stoma · root hair cell → xylem vessel → root cortex → stoma → mesophyll cell · root cortex → root hair cell → phloem tube → stoma → mesophyll cell · root hair cell → root cortex → phloem tube → mesophyll cell → stoma
5. Rung 5 · Pioneer · Year 11Over one day a person takes in 1800 mL of water in drinks, 700 mL in food and 250 mL made by respiration. They lose 1200 mL in urine, 450 mL in breath and 700 mL in sweat. If their body water stayed steady, how much was lost in faeces, in mL?
6. Rung 6 · Summit · Year 12In a root tip, 25 of the 200 cells examined are in mitosis. The whole cell cycle in this tissue lasts 24 hours. How long does mitosis itself last, in minutes?
7. Rung 7 · Apex · Year 13A tramper drinks very little all day, and their blood becomes more concentrated than normal. Which sequence describes the negative feedback that follows?The blood becomes too concentrated → the posterior pituitary releases more ADH → the kidney tubules reabsorb more water back into the blood → a small volume of concentrated urine is made and the blood returns to normal · The blood becomes too concentrated → the posterior pituitary releases less ADH → the kidney tubules reabsorb less water → a large volume of dilute urine is made and the blood becomes more concentrated still, until the tramper next stops for a drink · The blood becomes too concentrated → the posterior pituitary releases more ADH → the kidney tubules reabsorb less water so that the extra salt can leave → the blood becomes more concentrated still · The blood becomes too concentrated → the kidneys build extra water out of the salts they filter → that new water dilutes the blood → the urine volume never changes at all
8. Rung 8 · Beyond · NZ ScholarshipThe rate at which a gas diffuses across a surface is proportional to (surface area × concentration difference) ÷ thickness of the surface. Alveolus P has four times the surface area of alveolus Q, the concentration difference of oxygen across its wall is half as big, and its wall is twice as thick. By what factor is the rate of diffusion in alveolus P different from the rate in alveolus Q? (A rate that doubled would have changed by a factor of 2.)

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