Organisms and Populations quiz

In the logistic growth equation dN/dt = rN(K - N)/K, K stands for:

An age pyramid with a broad base indicates a population that is:

Which interaction is beneficial to one species and neutral to the other?

The fig tree is pollinated by:

Exponential growth of a population produces a:

The Abingdon tortoise in the Galapagos Islands became extinct due to competition with:

Lichens represent a mutualistic association between:

The human liver fluke completes its life cycle with the help of two intermediate hosts:

Monarch butterflies are distasteful to predators because they:

Which of the following increases population density?

How is the population size of tigers in a national park estimated? (2 marks)

Distinguish between natality and mortality. (2 marks)

What is intrinsic rate of natural increase (r)? Give one example of its value. (2 marks)

Why are predators important in an ecosystem? Give two reasons. (2 marks)

Explain the competition between flamingoes and fishes in South American lakes. (2 marks)

Describe resource partitioning as shown by MacArthur's warblers. (2 marks)

How does a cuckoo exploit a crow? Why does the crow not reject the cuckoo's eggs? (2 marks)

Give two examples of commensalism from the animal kingdom. (2 marks)

Why do Pacific salmon and bamboo breed only once in their lifetime? (2 marks)

Why is the logistic model considered more realistic than the exponential model? (2 marks)

In a population of 2,000 rabbits, there were 400 births and 150 deaths in a year, with no migration. Calculate the birth rate, death rate and the population at the end of the year. (3 marks)

A population grows exponentially with r = 0.1 per year. Starting with 1,000 individuals, calculate the population after 7 years (take e^0.7 = 2). Calculate the doubling time. (3 marks)

A logistic population has K = 2,000 and r = 0.5 per year. Calculate the growth rate dN/dt when N = 500, N = 1,000 and N = 2,000. (3 marks)

In 1981, the r value for the human population in India was 0.0205. Starting from a population of 68.3 crore in 1981, estimate the population increase in one year (using dN/dt = rN). (3 marks)

A quadrat survey of 10 quadrats of 1 square metre each in a meadow recorded 8, 12, 10, 6, 14, 9, 11, 7, 13 and 10 plants of a grass species. Calculate the mean density per square metre and estimate the population in a meadow of 500 square metres. (3 marks)

Read the passage and answer the questions. On a rocky coast of Scotland, the larger barnacle Balanus dominates the intertidal area and excludes the smaller barnacle Chthamalus from that zone. When Balanus was experimentally removed, Chthamalus spread into the area. (i) Name the interaction. (ii) Who conducted this study? (iii) Which principle does this support? (5 marks)

Read the passage and answer the questions. A census of a town shows that 45% of the population is below 15 years of age, 50% between 15 and 60 years, and 5% above 60 years. (i) Draw the age pyramid for this population. (ii) Classify the population as expanding, stable or declining. (iii) State one implication for the town's planning. (5 marks)

Read the passage and answer the questions. In a forest, a dodder plant (Cuscuta) was seen growing on a hedge plant. It had no leaves or chlorophyll and had special structures penetrating the host stem. (i) Name the interaction. (ii) Why has Cuscuta lost its chlorophyll and leaves? (iii) State two adaptations of parasites. (5 marks)

Read the passage and answer the questions. Cattle egrets are often seen foraging close to grazing cattle. As cattle move through vegetation, they flush out insects, which the egrets catch and eat. (i) Name the interaction. (ii) Which species benefits and how? (iii) Is the other species harmed? Explain. (5 marks)

Read the passage and answer the questions. A population of yeast grown in a closed flask increased slowly at first, then rapidly, and then levelled off as nutrients were depleted and waste accumulated. (i) Name the type of growth curve. (ii) Name the phases of the curve. (iii) What does the plateau represent? (5 marks)

Explain the exponential and logistic growth models with equations and labelled graphs. Explain the significance of r and K. (6 marks)

Describe the important attributes of a population. Draw labelled age pyramids for human populations and explain what each indicates. (6 marks)

Explain predation with examples, including its role in biological control. Draw a chart showing the defence mechanisms of prey against predators. (6 marks)

Explain the different types of population interactions with examples, and draw a chart showing the effect on each species (+, - or 0). (6 marks)

Explain mutualism with reference to lichens, mycorrhizae, fig and wasp, and Ophrys and bees. Draw a labelled diagram of any one example. (6 marks)