EXAM QUESTIONS

• (IMAGE) LAKE MALAWI IN EAST AFRICA HAS MORE SPECIES OF FISH THAN ANY OF LAKE IN THE WORLD (1).

  SUGGEST AND EXPLAIN HOW THIS SPECIATION MAY HAVE OCCURED.

  1. variations due to mutations
  2. allopatric speciation
  3. different lakes have different environmental conditions / different lakes
  4. reproductive isolation
  5. different alleles passed on
  6. eventually different species cant breed to produce fertile offspring

  
• (IMAGE) LOSS OF NUTRIENTS INTO LAKE MALAWI HAS RESULTED IN A DECREASE IN SOME FISH POPULATIONS (12-13). EXPLAIN WHY.

  1. growth of algae on surface of water blocks light
  2. no sun to plants means no photosynthesis so plants die
  3. saprobiontic microorganisms anaerobically respire
  4. less oxygen for fish to respire

  
• (IMAGE) THE MARK-RELEASE-RECAPTURE METHOD CAN BE USED TO ESTIMATE THE SIZE OF A FISH POPULATION (13-14). EXPLAIN HOW.

  1. capture/collect sample, mark and release
  2. ensure marking isn’t harmful, doesn’t effect its survival
  3. allow time for fish to distribute before collecting a second sample.
  4. population = number of fish in first sample * number in second Sample divided by number of marked fish in second sample / number recaptured

  
• (IMAGE) SUGGEST WHY THE MARK-RELEASE METHOD CAN PRODUCE UNRELIABLE RESULTS IN VERY LARGE LAKES (14-15)

  Less chance of recapturing fish / unlikely fish distribute randomly / evenly

  
• SUCCESSION OCCURS IN NATURAL ECOSYSTEMS. DESCRIBE AND EXPLAIN HOW SUCCESSION OCCURS.

  1. colonisation by pioneer species
  2. which change the environmental conditions eg. Forming soil
  3. environment becomes less hostile for new species
  4. increase in biodiversity
  5. to climax community
• (IMAGE) DESCRIBE HOW YOU COULD ESTIMATE THE SIZE OF A POPULATION OF SUNDEWS IN A SMALL MARSH?

  1. divide area into squares
  2. use a random number generator to create random coordinates
  3. count number of sundews in a quadrat
  4. obtain a large sample and calculate mean / average number per quadrat
  5. calculate total number of sundews by mean number of plants per Quadrat multiplied by number of quadrats.

  
• SUGGEST AND EXPLAIN HOW DIGESTING INSECTS HELPS THE SUNDEW TO GROW IN SOIL WITH VERY LOW CONCENTRATIONS OF SOME NUTRIENTS

  1. Digestion of proteins
  2. provided amino acids
  3. digestion of phosphate containing compound eg. DNA
  4. provided phosphate containing product eg. Nucleotides

  
• (IMAGE) DESCRIBE HOW YOU WOULD DETERMINE THE MEAN PERCENTAGE COVER FOR BEACH GRASS ON A SAND DUNE

  1. Use a random number generator to determine Position of quadrats
  2. large sample of qudrats
  3. divide total percentage by number of quadrats

  
• (IMAGE) THE SCIENTISTS CONCLUDED THAT THE RESULTS SHOWN IN FIGURE 1 WERE DUE TO SUCCESSION TAKING PLACE.

  USE FIGURE 1 TO EXPLAIN WHY THE SCIENTISTS REACHED THIS CONCLUSION.

  1. beach grass is the pioneer species
  2. pioneer species change the abiotic environment eg. More humus
  3. so less hostile / suitable for new species
  4. Conifer / hardwood trees represent climax community

  
• (IMAGE) USE FIGURE 1 TO EXPLAIN FIGURE 2

  Trees block / reduce sun light

  
• (IMAGE) EXPLAIN HOW USING THE SIT COULD REDUCED TRANSMISSION OF DENGUE

  1. compete with fertile males to mate / for food / resources - intraspecific competition
  2. Don’t reproduce

  
• (IMAGE) DESCRIBE HOW THE MARK-RELEASE-RECAPTURE METHOD COULD BE USED TO DETERMINE THE POPULATION OF A. AEGYPTI AT THE START OF THE INVESTIGATION.

  1. Capture mark and release
  2. lesve time for mosquitos to disperse before second sampling
  3. population = number in first sample * number in second sample divided by number of marked in second sample / number recaptured

  
• (IMAGE) THE RELEASE OF RADIATION-STERILISED A. AEGYPTI HAS NOT BEEN VERY SUCCESSFUL IN CONTROLLING THE TRANSMISSION OF DENGUE.

  SUGGEST ONE REASON WHY.

  radiation affects their courtship / survival / life span

  
• (IMAGE) SUGGEST WHY THE SCIENTISTS RELEASED MORE TRANSGENIC MALES EVERY WEEK

  to maintain number / competition as they due / have a short life span

  
• (IMAGE) THE RELEASE OF TRANSGENIC MALES PROVED SUCCESSFUL IN REDUCING THE NUMBER OF A. AEGYPTI.

  DESCRIBE HOW THE RESULTS IN THE DIAGRAM SUPPORT THIS CONCLUSION.

  The number of mosquitos in the treated area is lower after 12 weeks

  
• (IMAGE) EXPLAIN HOW THE DATA IN THE TABLE PROVIDES EVIDENCE OF SUCCESSION

  1. overall there is an increase in species richness
  2. Baetis quilleri and pentaneurini guttipennis are pioneers.
  3. pioneers cause a change in the environment eg. Provide food for other species
  4. new species colonise once there is a change
  5. previous species eg. Baetis quilleri are outcompeted as succession continues

  
• THE STREAM EVENTUALLY RECOVERED TO REACH A CLIMAX COMMUNITY.

  GIVE TWO FEATURES OF A CLIMAX COMMUNITY.

  1. same species present over a long times / stable community
  2. abiotic factors more constant over time
  3. populations stable around carrying capacity

  
• (IMAGE) WHAT CAN YOU CONCLUDE FROM THESE DATA ABOUT THE EFFECTS OF HUMAN ACTIVITIES ON BIODIVERISTY?

  1. only cleared and abandoned and introduction of non-native species make significant difference
  2. because only means of these 2 SDS from zero / no change
  3. about same number / 4 to 3 increase or decrease of species richness

  
• (IMAGE) SUGGEST AN EXPLANATION FOR THE EFFECT SIZE WHEN NON-NATIVE SPECIES WERE INTRODUCED TO COMMUNITIES.

  1. non-native species outcompetes / kills / eats / is a disease of native plants
  2. some native species become extinct in the community

  
• DESCRIBE HOW YOU WOULD INVESTIGATE THE EFFECT OF AN INVASION BY A NON-NATIVE SPECIES OF PLANT (A BIOTIC ENVIRONMENTAL FACTOR) OVER MANY YEARS ON THE ABUNDANCE OF A NATIVE SPECIES OF PLANT IN A COMMUNITY

  1. set up a grid system 


  with coordinates

  1. place large number of quadrats at coordinates selected at random
  2. count number of native plant in quadrants
  3. Repeat at same time each year for many years

  
• IN NORTHERN INDIA THERE IS A CONFLICT OF INTERESTS BETWEEN FARMERS OF LIVESTOCK (EG. COWS) AND PEOPLE TRYING TO CONSERVE IBEX (A TYPE OF WILD GOAT).

  WHEN LIVESTOCK ARE GIVEN EXTRA FOOD, THEIR POPULATIONS CAN GROW TOO LARGE AND COMPETE WITH IBEX.

  NAME THE TYPE OF COMPETITION BETWEEN LIVESTOCK AND IBEX.

  Interspecific competition
• (IMAGE) USING ALL THE INFORMATION, SUGGEST AND EXPLAIN THREE ACTIONS THAT THE FARMERS COULD TAKE TO ACHIEVE THIS BALANCE.

  1. don’t provide the livestock with extra food as their populations will not grow large enough to cause. Competition.
  2. choose other animals other than horse to farm as they have the same habitat and similar food to the ibex
  3. keep horses in separate areas, as they occupy the same habitats as ibex
  4. farm cows / yaks as they have the least similar food and one of the least similar habitat to the ibex
  5. Only grow crops so no competition

  
• (IMAGE) DESCRIBE HOW SHE COULD USE THESE MATERIALS TO SEPARATE THE PHOTOSYNTHETIC PIGMENTS BY CHROMATOGRAPHY

  1. draw line on chromatography paper using the pencil and ruler
  2. use pipettes to add solution to line
  3. add solvent A below the line
  4. remove from the glassware before solvent reaches the end of the chromatography paper and mark where the solvent reaches