Practise IB Biology HL C4.1 by selecting sampling methods, interpreting growth and food-web data, and reasoning about interactions between species.
The photograph shows Japanese knotweed, Reynoutria japonica, which is native to Japan, China and Korea. It has been introduced into other regions of the world and is now an invasive alien species in parts of Europe and North America. Dense groups of stems often develop with a height of up to 3 metres, which prevent other plants from growing.
State the biological term for a group of organisms of the same species living in an area.
Suggest two ways in which a plant such as Reynoutria japonica could prevent the growth of other plants.
The Atlantic cod is considered in many countries to be endangered due to overfishing. Describe two methods that could be used to estimate the cod population.
White sage (Salvia apiana) is a native Californian shrub. Slender oat (Avena barbata) is a grass, originally from the Mediterranean, which was introduced to California. The map shows the distribution of the two species in relation to one another in an area near Santa Ynez, California.
Using the scale bar, determine the area of quadrat A1, giving the units.
Outline how chi-squared can be used to test for an association between the distributions of the two species.
The photograph shows Japanese knotweed, Reynoutria japonica, which is native to Japan, China and Korea. It has been introduced into other regions of the world and is now an invasive alien species in parts of Europe and North America. Dense groups of stems often develop with a height of up to 3 metres, which prevent other plants from growing.
State the biological term for a group of organisms of the same species living in an area.
White sage (Salvia apiana) is a native Californian shrub. Slender oat (Avena barbata) is a grass, originally from the Mediterranean, which was introduced to California. The map shows the distribution of the two species in relation to one another in an area near Santa Ynez, California.
Using the scale bar, determine the area of quadrat A1, giving the units.
The diagram shows levels of DDT, a pesticide, in an aquatic food web in Lake Kariba, Africa. Numbers represent ppm (parts per million) of DDT in fat tissue.
Outline how the population size of tilapia could be estimated.
Outline the effect of carrying capacity on the growth of a population.
The prickly pear cactus (Opuntia stricta) was first recorded in Kruger National Park, South Africa, in 1950 . It spread rapidly, mainly through seeds being dispersed by baboons and elephants.
In 1997, the cactus moth (Cactoblastis cactorum) from South America was introduced into the area as a biological control. The larvae of the moth feed on the cactus. The graph shows the number of cladodes (flattened stem sections) of cactus found per in the years before and after the introduction of the cactus moth.
Explain the change in numbers of the cactus moth throughout the study period.
Explain the factors that can contribute to the exponential growth phase in a sigmoid population curve.
Duckweed (Lemna aequinoctialis) is a small floating plant that sometimes forms a continuous cover over the surface of ponds. In an experiment, it was grown either in nutrient-rich medium or in sewage water for four weeks. The biomass obtained per square metre at different times is shown in the population growth curves.
Label two phases on the nutrient-rich medium population growth curve.
The pavement ant (Tetramorium caespitum) eats organic matter found within its territory. Individual ants leave their nest to forage for food. When they find a suitable source of food they return and communicate to other ants in the colony where the food can be found. The diagram shows the path of one ant when foraging for food and returning to the nest after finding food.
State one advantage to an insect of living in a colony.
Over time, the hull of a sunken ship may become colonized by a wide range of marine organisms. What term is used to describe all of the organisms living in and on a sunken ship?
A community
An ecological niche
A population
An ecosystem
The photograph shows Japanese knotweed, Reynoutria japonica, which is native to Japan, China and Korea. It has been introduced into other regions of the world and is now an invasive alien species in parts of Europe and North America. Dense groups of stems often develop with a height of up to 3 metres, which prevent other plants from growing.
Suggest two ways in which a plant such as Reynoutria japonica could prevent the growth of other plants.
Most reef-building corals contain photosynthetic algae, called Zooxanthellae, that live in their cells. Coral bleaching can occur as a result of human-induced changes leading to the Zooxanthellae being ejected from the coral.
State the type of interaction that occurs between Zooxanthellae and reef-building corals.
The prickly pear cactus (Opuntia stricta) was first recorded in Kruger National Park, South Africa, in 1950 . It spread rapidly, mainly through seeds being dispersed by baboons and elephants.
In 1997, the cactus moth (Cactoblastis cactorum) from South America was introduced into the area as a biological control. The larvae of the moth feed on the cactus. The graph shows the number of cladodes (flattened stem sections) of cactus found per in the years before and after the introduction of the cactus moth.
Outline how the prickly pear cactus may become an ecological problem in Kruger National Park.
In South Korea, flocks of birds of the tit family (Paridae) forage together on trees for food. Researchers observed four species of Paridae to determine whether they shared the same habitat in the trees and whether their position on the tree depended on their size. The leafy part of the tree (crown) was divided into nine sections, three according to height from the ground and three according to the distance from the tree trunk. Observations were also made of birds foraging in the bushes surrounding the trunk and on the ground below the tree. The chart shows the relative use of each section of the habitat by the birds.
Discuss whether the results for the Varied Tit and Coal Tit indicate competitive exclusion.
White sage (Salvia apiana) is a native Californian shrub. Slender oat (Avena barbata) is a grass, originally from the Mediterranean, which was introduced to California. The map shows the distribution of the two species in relation to one another in an area near Santa Ynez, California.
Outline how chi-squared can be used to test for an association between the distributions of the two species.
The shore crab (Carcinus maenas) forages for food in the intertidal zone on rocky seashores. An experiment was carried out to assess predation at specified levels of food abundance. An area of shore was enclosed in a wire cage. All other food was removed from the encaged area except the mussels provided by the investigators. The number of mussels consumed was measured while the crabs foraged at densities of one, two or four crabs per cage.
Suggest a reason for the plateau in the graph when only one crab is present in the cage.
Determine whether foraging by crabs is dependent on number of prey (mussels) or number of predators (crabs).
An investigation into food web interactions was conducted in mesocosms in the Mediterranean Sea, off the coast of France. The effects of the addition of soil and fish on bacterial populations were tested.
Assuming that the populations of bacteria are under bottom-up control, identify the mesocosms in which the bacterial populations will be highest.
Outline top-down effects on the bacteria in the four mesocosms.
The image shows mycorrhizal fungi growing between the cells of a recently germinated orchid plant.
Explain how a named plant can reduce competition by allelopathy.