CBSE Questions for Class 12 Medical Biology Organisms And Population Quiz 15 - MCQExams.com

The population size of a species over time is shown in the graph. The growth pattern demonstrated by the population at time 1 is

480416_588b5b1827904c3da499911665f443d1.png
  • Gradual
  • Declining
  • Continual
  • Oscillating
  • Exponential
Which one of the following pair of animals is an example of commensalism?
  • Sacculina- Crab
  • Plasmodium- Anopheles
  • Golden Jackal- Tiger
  • Ascaris- Man
Gause's principle of competitive exclusion states that
  • More abundant species will exclude the less abundant species through competition.
  • Competition for the same resources excludes species having different food preferences.
  • No two species can occupy the same niche indefinitely for the same limiting resources.
  • Larger organisms exclude smaller ones through competition.
Which of the following could not cause a large number of density-dependent deaths in a population?
  • Winter storms
  • Disease carrying insects
  • Predators
  • Limited resources
  • Small forest fire
The interspecific relationship which benefits one species and harms the other includes
I. Commensalism
II. Competition
III. Parasitism
IV. Predation
  • III only
  • III and IV
  • I, II, and III
  • II, III, and IV
  • I, II, III, and IV
If lynxes depend mainly on hares for food, the relationship between hares and lynxes is described by

486951_b6b86a00659d4f8ba8fe3b6a7d6f4384.png
  • As the hare population decreases, the lynx population increases
  • As the hare population decreases, the lynx population stays the same
  • As the hare population increases, the lynx population increases
  • As the hare population increases, the lynx population stays the same
  • There is no relationship between the populations of lynxes and hares.
Which of the following will be fewer in number for an invasive species in a new ecosystem?
I. Ecological niches
II. Predators
III. Suitable food sources
  • I only
  • II only
  • III only
  • I and II
  • II and III
The point of time in the graph when the population size reaches the carrying capacity for ecosystem is

481344_80575fd68679414da14fb47161c75e77.png
  • 3
  • 4
  • 6
  • 9
  • 12
In what way a plant growing on a forest floor is adapted for its survival?
  • Has shallow roots
  • Requires low light
  • Has a deep ta root
  • Requires strong light
  • Requires moist soil
Based on the given figure, find out the incorrect statement?
485646.png
  • Rodent density is dependent on food-species diversity
  • Food- species diversity is dependent on rodent density
  • Grazing pressure maintains food-species diversity
  • Rodents are selective in their food choices
  • Rodents help prevent food-species mono cultures from developing
An individual in local hawk populations must increasingly compete for a limited number of nesting sites. This is an example of
  • A convergent dispersion pattern within the population
  • A uniform dispersion pattern within the population
  • A random dispersion pattern within the population
  • A clumped dispersion pattern within the population
  • Multiple individuals simultaneously occupying the same nest
The population growth represented by graph shows
481352_7b805af2f108423588a5ff1548284107.png
  • No growth
  • Slow growth
  • Slow decrease
  • Rapid increase
  • Rapid decrease
The given graph represents the fastest multiplication rate of bacteria when they are added to rich broth.
The following graphs represent bacterial growth under different conditions, with increasing numbers of bacteria on the $$y$$-axis and increasing time on the $$x$$-axis.
Which graph describes the result of introduction of minimal nutrients for the first six hours and then addition of surplus nutrients?

484257_21416e81e37d42a1b679f6bfeecd6fd2.png
  • 1
  • 2
  • 3
  • 4
  • 5
Which of the following depicts, the two organisms that occupy many of the same niches?
  • Mutualistic partners
  • Predator-prey
  • Host-parasite
  • Competitors
  • Commensalistic partners
In symbiotic relationships, groups of two or more organisms live in physical proximity. The types of symbiosis that depicts commensalism is
  • An egret riding on the back of a cow, looking for food in cow patties
  • A little bird riding on the back of a rhino, picking parasites off the back of the rhino
  • Undertaker bees removing dead bees from the hive of worker bees
  • A wrasse cleaning the parasites off the gills of a bigger fish
  • All of the above are commensalistic
Read the passage and answer the following question.
An investigator went to Central America to study oropendolas, which are communal nesting birds. Another species of bird, the cowbird, sometimes lay its eggs in the nests of oropendolas. Some of the populations of oropendolas throw the cowbird eggs out of the nest, and some don't. The investigator was interested in finding out why some birds would raise other species as their own but others would toss them out. By watching the nests closely, he found that blowflies lay their eggs in the nests of oropendolas and that the young larvae, maggots, feed on the young birds. If young cowbirds are in the nest, the precocious cowbirds eat the blowfly larvae, protecting the young oropendolas. In colonies of oropendolas that discriminate against cowbirds, throwing them from the nest, the blowflies are not eaten by cowbirds. These colonies of oropendolas build their nests close to a particular wasp colony, and the wasps eat the blowflies.
The relationship between the blowfly and the cowbirds that are associated with the non-discriminating oropendolas is one of
  • Commensalism
  • Predation
  • Mutualism
  • Competition
  • Amensalism
A larger, more aggressive blackbird sees a younger, smaller blackbird discover a food resource. He flies down, taking the food from the younger bird, is best explaine by
  • A selfish act
  • An altruistic act
  • A spiteful act
  • A cooperative act
  • An unsocial act
Which of the following is associated with Lynn Margulis's endosymbiotant theory?
  • Mitochondria DNA is more like that of bacteria than the nuclear DNA in human cells.
  • Chloroplasts replicate on their own time schedule, not under nuclear control.
  • Mitochondria and chloroplasts are about the same size as prokaryotes.
  • All of the above.
  • None of the above.
The relationship between the species of columns 1 and 2 describes
491735_6dec8aa35bd045a096aad1b1fec9ec00.png
  • The species in column 1 help to determine which species are in column 2
  • The species in column 2 help to determine which species are in column 1
  • The species in column 1 are dependent on the species in column 2
  • The species in both columns 1 and 2 help to determine the climate of the area
  • None of the above 
Read the passage and answer the following question.
A student studying respiration decided to test the following hypothesis: "If yeasts use glucose for energy, then the more glucose I add to their medium, the more the population will grow.
"To test this hypothesis, she filled four tubes with $$5 ml$$ of minimal growth media and added no glucose to the first, $$5 ml$$ to the second, $$10 ml$$ to the third, and $$20 ml$$ to the fourth. After 1 day she recorded the following data:
According to data, which of the following statement is true?
491559_d2ced0ee47ca4d5da543cbe2c4cfc9fa.png
  • Yeasts need glucose to grow
  • The more glucose given to yeasts, the better they will grow
  • pH can be used to measure the rate of growth
  • Yeasts give off hydrochloric acid when they grow
  • None of the above
Competition between the members of a woodchuck population in a large field is increased by the increase in
  • Woodchuck reproduction rate
  • Spread of disease among the woodchucks
  • Number of woodchucks killed by cars
  • Number of secondary consumers
  • Natality rate of their predators
An investigator went to Central America to study oropendulas, which are communal nesting birds. Another species of bird, the cowbird, sometimes lay its eggs in the nests of oropendulas. Some of the populations of oropendulas throw the cowbird eggs out of the nest, and some dont. The investigator was interested in finding out why some birds would raise other species as their own but others would toss them out. By watching the nests closely, he found that blowflies lay their eggs in the nests of oropendulas, and that the young larvae, maggots, feed on the young birds. If young cowbirds are in the nest, the precocious cowbirds eat the blowfly larvae, protecting the young oropendulas. In colonies of oropendulas that discriminate against cowbirds, throwing them from the nest, the blowflies are not eaten by cowbirds. These colonies of oropendulas build their nests close to a particular wasp colony, and the wasps eat the blowflies.
The relationship between the oropendulas that discriminate against cowbirds and the cowbirds is one of
  • Commensalism
  • Predation
  • Mutualism
  • Competition
  • Amensalism
Read the passage and answer the following question.
An investigator went to Central America to study oropendolas, which are communal nesting birds. Another species of bird, the cowbird, sometimes lay its eggs in the nests of oropendolas. Some of the populations of oropendolas throw the cowbird eggs out of the nest, and some don't. The investigator was interested in finding out why some birds would raise other species as their own but others would toss them out. By watching the nests closely, he found that blowflies lay their eggs in the nests of oropendolas and that the young larvae, maggots, feed on the young birds. If young cowbirds are in the nest, the precocious cowbirds eat the blowfly larvae, protecting the young oropendolas. In colonies of oropendolas that discriminate against cowbirds, throwing them from the nest, the blowflies are not eaten by cowbirds. These colonies of oropendolas build their nests close to a particular wasp colony, and the wasps eat the blowflies.
The relationship between the oropendolas and the cowbirds is 
  • Commenslism
  • Predation
  • Mutualism
  • Competition
  • Amensalism
The greatest number of thorns per plant are found in 
497100.jpg
  • Unfenced, year 0
  • Unfenced, year 1
  • Unfenced, year 2
  • Fenced, year 1
  • Fenced, year 2
Choose the correct statement that best explains the data.
497100.jpg
  • H. spinosa grows thorns in response to grazing.
  • H. spinosa thorns are involved in reproduction.
  • Grazing selects for plants with a greater number of thorns.
  • Grazing decreases the number of thorns on H. spinosa plants.
  • Plants with more thorns have greater fitness than plants with fewer thorns.

What relationship between two populations can you reasonably deduce when comparing curves I and II?
495194.png
  • The relationship is neutral
  • There is strong evidence of competition but with resource partitioning
  • The population designated II appears to be an invasive species that outcompetes the other
  • The population designated I appears to be an invasive species that could not survive in a new niche
  • The population designated II appears to be a parasitic species that uses the other as its host.
The best explanation for the change in the distribution of Chthamalus observed $$3$$ months after removal of the larger Balanus individuals is that
497767.jpg
  • Balanus feeds on Chthamalus larvae.
  • Balanus does not reproduce as quickly as Chthamalus.
  • Balanus has less tolerance for wet conditions.
  • Balanus adults are mobile.
  • Balanus is less susceptible to predators.
A fungus that lives symbiotically with plants is
  • Mycorrhizae
  • Lichens
  • Mushrooms
  • Morels
  • Truffles
The carrying capacity of an environment in the given population growth curve is represented by
500331_3600294005644d54845e7d2a710eed8c.png
  • I
  • II
  • III
  • IV
  • V
Large number of eggs are produced by a spider species but due to little parental care, only a few of them reach adulthood. The line representing the survivorship curve for this species is
497071.jpg
  • Curve 1
  • Curve 2
  • Curve 3
  • Curves 1 and 2
  • Curves 1 and 3
The origin of the predation ability of Venus flytraps is explained by
  • Only those plants with the ability to supplement the poor nutrient content of their soils could survive.
  • Predation allowed the Venus flytrap to outcompete other species because of its ability to move rapidly.
  • As consumers instead of produces, Venus flytraps have greater access to better nutrients.
  • Predation allowed the Venus flytrap to collect a wider variation of preformed organic materials.
  • Better nutrients allowed the Venus flytrap to grow faster than other plants.
What is true about the relationship between hare and lynx if lynxes depend mainly on hares for food?
500749.png
  • As the hare population decrease, the lynx population increase.
  • As the hare population decrease, the lynx population stays the same.
  • As the hare population increase, the lynx population increase.
  • As the hare population increase, the lynx population stays the same.
  • There is no relationship between the population of lynx and hares.
Which best illustrates the competitive exclusion principle?
  • Mushrooms grow and break down a rotting log found in a moist shady area of a forest.
  • Lichens and pioneer species are replaced by mosses and grasses, followed by tree saplings and shrubs and eventually tall deciduous trees.
  • An orchid grows upon the branches of a tree and absorbs water and minerals from rainwater runoff.
  • Three species of warblers feed on different regions of the same tree.
  • A bear catches and consumes a salmon.
Connel's field experiment on the rocky sea coast of Scotland, where larger Barnacle balanus dominates the intertidal area and removes the smaller Barnacle cathamalus. This happened due to.
  • Predation
  • Competition
  • Parasitism
  • Mutualism
A population is correctly defined as having which of the following characteristics?
a. Inhabiting the same geography area.
b. Individual belonging to same species.
c. Possessing a constant and uniform density and 
dispersion.
  • a and b only
  • b and c only
  • a and c only
  • b only
The interaction between the organisms of one of the following pairs is an example for commensalism
  • Wasps and fig tree
  • Cuscuta with other plant
  • Cattle or sheep and egrets
  • Ascaris and human 
Which of the following describes a random event?
  • A group of peafowl are nesting in a forested area. During a monsoon a large chunk of wood lands on one of the peacocks.
  • A peafowl with drab coloring escapes a predator by hiding in tall grasses.
  • A tiger catches a peacock by his long, beautiful tail and eats him.
  • When a blood parasite spreads through a peafowl population, the individuals with a certain protein on their blood cell surface survive at a higher rate than those without the protein.
Insects constitute the largest animal group on earth. About 25-30% of the insect species ate known to be herbivores. In spite of such huge herbivore pressure, globally, green plants have persistence. One possible reason for this persistence is:
  • Food preference of insects has tended to change with time
  • Herbivore insects have become inefficient feeders of green plants
  • Herbivore population has been kept in control by predators
  • Decline in reproduction of herbivores with time
Mac Arthurs vision of five closely related species of warbles living on same tree were able to avoid competition and co-exist by behavioural difference. This is an example for
  • Competitive release
  • Resource partitioning
  • Competitive exclusion principle
  • Adaptive radiation
Volume and surface area of a deer is 1,50,000 c$$m^3$$ and 19,000 c$$m^2$$ and of a squirrel is 625 c$$m^3$$ and 530 c$$m^2$$. The area available for heat loss per c$$m^3$$ of squirrel will be approximately
  • Seven times more than the deer
  • Eleven times less than the deer
  • Three times more than the deer
  • Eleven times more than the deer
What do you means by potential natility?
  • Number of organism in a blame.
  • Natural increase of population under optimum condition/concentration.
  • Net potential of organism in a blame.
  • Maximum member of organisms in a population.
The number of children born to an average woman in a population during her entire reproductive life is called as
  • Fertility
  • Birth rate
  • Total fertility rate
  • Population growth rate
Which one causes parasitic castration in crab?
  • Spongilla
  • Adamsia
  • Sacculina
  • None of the above
Density of population (D) is 
  • $$D=\dfrac{S(size)}{W (weight)}$$
  • $$D=\dfrac{S(space)}{N (Number)}$$
  • $$D=\dfrac{N(number)}{S (space)}$$
  • None of the above
Study statements (a - d) and select the two correct statements. 
(a) A lion eating a deer and a sparrow feeding on grain are consumers.
(b) Predator starfish and Pisaster help in maintaining species diversity of some invertebrates.
(c) Predators ultimately lead to the extinction of prey species.
(d) Plant chemicals like nicotine and strychnine are produced due to metabolic disorders. 
  • c and d
  • a and d
  • a and b
  • b and c
The given statement "Complete competitors cannot coexist " is true for 
  • Primary succession
  • Secondary succession
  • Character displacement
  • Competitive exclusion
Which of the following is not properly matched?
  • Formaldehyde- Carcinogenic
  • Sulphur dioxide - Respiratory problems
  • Nitrogen oxide - Brown air
  • Mean annual temperature - $$25^o$$C
  • Photochemical smog - Grey air
Population of an insect species increases explosively during rainy season and then disappears at the end of the season. It shows 
  • Food plants mature and die at the end of rainy season
  • Population of predators increases enormously
  • Population growth curve is J-shaped
  • Population growth curve is S-shaped
Calculate the death rate if $$6$$ individuals in a lab population of $$60$$ fruit flies died during a particular week?
  • $$0.2$$
  • $$0.1$$
  • $$1$$
  • $$5$$
Scholars caught, marked and released 80 fishes in a pound. Later 100 fishes were caught at random. 40 of them were marked. The number of fishes in the pond is 
  • 400
  • 200
  • 100
  • 50
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 12 Medical Biology Quiz Questions and Answers