Note AcademyNote Academy
Start

Biology · Oct / Nov 2025 · Paper 41 · Question 3

0610

As printed in the paper

The question as text

Fig. 3.1 is a diagram of the nitrogen cycle. proteins in plants and animals nitrogen in the atmosphere plant and animal waste amino acids in plants and animals compound Y decomposition nitrogen fixation A assimilation B nitrate ions in soil Fig. 3.1

Read automatically from the paper; the printed page above is exact.

Show the answer and mark scheme

  • 3(a)(i)[2]

    A denitrification ;

    B nitrification ;

  • 3(a)(ii)[2]

    any two from:

    lightning ;

    bacteria ;

    AVP ;

  • 3(a)(iii)[1]

    ammonia / ammonium (ions) ;

  • 3(a)(iv)[1]

    liver ;

  • 3(a)(v)[2]

    removal of nitrogen containing part

    (of amino acids / protein) ;

    urea is formed ;

  • 3(b)[5]

    greenhouse effect ;

    rice ;

    carbon dioxide ;

    photosynthesis ;

    burning / combustion ;

  • 3(c)[6]

    any six from:

    1

    untreated sewage / fertiliser / nutrients ;

    2

    increased availability of nitrates / ions / AW ;

    3

    causing algal bloom / algae reproduction ;

    4

    algae reduce (penetration of) sunlight (in the water) / AW ; 5

    (so rooted) plants unable to photosynthesise ;

    6

    so plants die ;

    7

    bacteria, decompose / feed, on dead, plants or algae ;

    8

    so bacterial populations increase ;

    9

    bacteria respire aerobically ;

    10 bacteria use up the oxygen in the water ;

    11 organisms / fish , die / suffocate / migrate, due to lack of oxygen ;

Practise this paper →

Make a free account to save your answers and see your weak topics and ask the AI why a wrong answer is wrong.