Practise IB Biology SL C4.1 by estimating populations, reading community and growth data, and testing species interactions with quadrat and statistical evidence.
75 questions in this syllabus scope, with question parts counted together.
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In a rock pool a student observes four different species of animal. She sees 43 flat periwinkles (Littorina littoralis), ten rough periwinkles (Littorina saxatilis), three shore crabs (Carcinus maenas) and one common goby (Pomatoschistus microps).
How many populations and communities did she see in the pool?
Populations
Communities
1
4
2
3
3
2
4
1
In an area of forest measuring 100 m by 100 m , samples were taken to estimate the number of silver maple (Acer saccharinum) trees in the forest. The number of trees counted in each of five areas of was recorded.
Approximately how many silver maple trees are in the area of forest?
5
25
125
625
The table shows the numbers of five different species of algae growing in the River Trent in the United Kingdom from May to October 1939, at different distances from where untreated sewage had entered the river.
Describe one method that could have been used to record the number of algae along the River Trent.
A capture-mark-release-recapture experiment was used, together with the Lincoln index formula (population size estimate ), to estimate the population size of common periwinkles (Littorina littorea) on a rocky shore. The table shows the data collected.
What is the estimated size of the population?
160
500
1000
5000
The graph shows a predicted population growth curve when a small number of rats are accidentally introduced to an island where they do not naturally occur. When is there most likely to be a balance between natality and mortality?
The graph shows a population growth curve.
What factor could cause the part of the graph indicated by X ?
Increased food supply
Increased disease
Reduced predation
Reduced competition
The graph shows the growth of a population of rabbits inhabiting a new area.
What would be suitable labels for the axes X and Y ?
X
Y
number of rabbits
time
time
birth rate of rabbits
birth rate of rabbits
time
time
number of rabbits
No public sample questions are available for this syllabus point yet.
A group of nine semi-wild Asian elephants (Elephas maximus) from an elephant camp in Myanmar were trained to pull two ends of a single rope to get access to food in food trays located on a table behind a barrier. When both elephants pulled the rope, the table moved towards them making the food trays accessible. The task required two elephants to work together in cooperation for mutual benefit to obtain food.
The graph shows the rate of cooperation between pairs of elephants in pulling the rope when there were two food trays, one at each end of the table (as shown in the diagram), or when there was one food tray placed in the centre of the table. The cooperation rate was the number of successful cooperative attempts divided by the number of all attempts in one session. The experiment was repeated for many sessions on successive days.
Using the graph, describe how the elephants cooperated when two food trays were available.
Outline the reason that the one-tray experiment was carried out for fewer sessions than the two-trays experiment.
Suggest a reason for the difference in the response of the elephants between the two-tray and one-tray experiments.
Compare and contrast the frequency of monopoly and fighting when there is a change from two trays to one tray of food.
Suggest a reason for the observed changes in competition.
The probability of a fight occurring between two elephants depends on differences in their dominance rank in the group. Rank difference was calculated using the rank of the elephant starting the fight minus the rank of the target elephant. The researchers modelled a graph of the probability of elephants fighting back when another elephant attempted to start a fight if presented with two trays or one tray of food.
Estimate the probability of a fight occurring when an elephant of rank 5 initiates a fight with an elephant of rank 2 if they are presented with two trays of food.
Compare and contrast the chances of a fight occurring with two trays and one tray of food.
How are the individuals in an ecological community related to each other?
They all belong to the same species.
They all belong to the same trophic level.
They belong to different populations.
They belong to populations composed of many species.
Which interspecific relationship has a negative impact on both individuals?
Competition
Mutualism
Parasitism
Pathogenicity
Root nodules in a plant of the Fabaceae (legume) family is an example of a type of interspecific relationship that involves bacteria.
Which of the following explains the relationship between the species?
It is mutualistic, as bacteria obtain oxygen for respiration and provide carbon dioxide for plant photosynthesis.
It is mutualistic, as the plant supplies bacteria with sugars and obtains ammonium for protein synthesis.
It is parasitic, as bacteria take nutrients from the plant causing poor plant growth.
It is parasitic, as bacteria obtain water from roots, which reduces plant photosynthesis.
The red lionfish (Pterois volitans) is an aggressive predator that inhabits coral reefs. It is native to the Indo-Pacific ocean but has recently been found in Florida, the Gulf of Mexico and the Caribbean and is considered to be an invasive species.
Discuss the impact that the presence of this fish could have in the Gulf of Mexico.
Caenorhabditis elegans and Caenorhabditis briggsae are two species of nematode that co-exist in rotting plant material. A study was conducted in France to determine the relative population of each species in samples of apples.
Suggest, with a reason, the type of interaction that may exist between the two nematodes.
A student wanted to know whether the density of buttercup (Ranunculus) flowers in two fields was the same. He used a quadrat to estimate the number of flowers in equal-sized areas of each field. The table shows the results.
| Number of flowers | Field 1 | Field 2 |
|---|---|---|
| Observed | 75 | 51 |
| Expected | 63 | 63 |
A chi-squared test was carried out to determine whether the density of buttercups was the same in both areas. The chi-squared calculated value was 4.571 .
With reference to the probability table, what conclusion can be drawn about the null hypothesis with 95 % confidence?
It is rejected as 4.571 is less than 5.991.
It is rejected as 4.571 is greater than 3.841.
It is rejected as 4.571 is greater than 0.455 .
It is rejected as 4.571 is greater than 1.386.
The mountain yellow-legged frog (Rana muscosa) was once a common inhabitant of the Sierra Nevada (California, USA). It has declined during the past century due in part to the introduction of non-native fish, such as trout, into naturally fish-free habitats. The bar chart shows the average number per lake of tadpoles (aquatic larval stage) and frogs in lakes with and without trout in 1996.
Compare results for lakes with and without trout.
The trout might affect the number of frogs or tadpoles by competing for resources. Suggest one other way in which trout might affect the number of tadpoles or frogs in lakes.
Describe the effect of removing trout on frog density in Upper and Lower LeConte Lakes.
Using the map and graph, predict whether the removal of the trout from Upper and Lower LeConte Lakes will lead to a permanent recovery in the number of frogs and tadpoles.
What will happen to the sizes of the populations in the food web above if the sea otter disappears?
Large fish increase and sea urchins decrease.
Abalones increase and sharks increase.
Sea urchins increase and kelps decrease.
Sea stars decrease and sharks increase.
The paradise tree (Ailanthus altissima) produces a chemical called ailanthone which inhibits the growth of other plants. What is this process?
Allelopathy
Endemism
Mutualism
Herbivory
