With the help of suitable diagram describe the . ; logistic population growth curve.
The S-shaped growth curve is also called a logistic growth curve. It describes a situation in which (in a new environmental condition) the population density of an organism increases slowly establishing itself then increasing rapidly, approaching an exponential growth rate. Many population of micro-organisms broadly follow this basic sigmoidal pattern. For example, when a fresh culture medium is inoculated with bacteria, sigmoidal or S-shaped growth curve is observed. The S-shaped curve is generated when a population approaches the environmental's carrying capacity. Carrying capacity is the maximum number of individuals of a population that can be supported in a given time.
The S-shaped growth form is represented by the following equation- ” dNldt = rN[K-NIK]
Where, r = intrinsic rate of natural increase N = population density at time t K = carrying capacity
Why do all the fresh water organisms have contractile vacuoles whereas , majority of marine organisms lack them?
Define the following terms and give one example for each:
(a)Commensalism (b)Parasitism
(c)Camouflage (d)Mutualism
(e)Interspecific competition
In a sea shore, the benthic animals live in sandy, muddy and rocky substrata
and accordingly developed the following adaptations.
a. Burrowing
b. Building cubes
c. Holdfasts/peduncle
Find the suitable substratum against each adaptation.
Lianas are vascular plants rooted in the ground and maintain erectness of their stem by making use of other trees for support. They do not maintain direct relation with those trees. Discuss the type of association the lianas have with the trees.
Give an example for:
(a)An endothermic animal
(b)An ectothermic animal
(c)An organism of benthic zone
Write a short note on
(a)Adaptations of desert plants and animals
(b)Adaptations of plants to water scarcity
(c)Behavioural adaptations in animals
(d)Importance of light to plants
(e)Effect of temperature or water scarcity and the adaptations of animals.
In a pond, we see plants which are free-floating; rooted-submerged; footed emergent; rooted with floating leaves. Write the type of plants against each of them.
Does light factor affect the distribution of organisms? Write a brief note giving suitable examples of either plants or animals.
The following diagrams are the age pyramids of different populations. Comment on the status of these populations.
Most living organisms cannot survive at temperature above 45 °C. How are some microbes able to live in habitats with temperatures exceeding 100 °C?
Why are coral reefs not found in the regions from. West Bengal to Andhra Pradesh but are found in Tamil Nadu and on the east coast of India?
Give one example for each of the following types.
(a) Migratory animal (b) Camouflaged animal
(c) Predator animal (d) Biological control agent
(e) Phytophagous animal (f) Chemical defense agent
What is the ecological principle behind the biological control method of managing with pest insects?
Why do high altitude areas have brighter sunlight and lower temperatures as compared to the plains?
An individual and a population has certain characteristics. Name these attributes with definitions.
In an aquarium two herbivorous species of fish are living together and feeding on phytoplanktons. As per the Gause's Principle, one of the species is to be eliminated in due course of time, but both are surviving well in the aquarium. Give possible reasons.
Which element is responsible for causing soil salinity? At what concentration does the soil become saline?
Observe the set of 4 figures A, B, C and D, and answer the following questions: •
(i) Which one of the figures shows mutualism?
(ii) What kind of association is shown in D?
(iii) Name the organisms and the association in C.
(iv) What role is the insect performing in B?
If a marine fish is placed in a fresh water aquarium, will the fish be able to survive? Why or why not?
a. Label the three tiers 1, 2, 3 given in the above age pyramid.
b. What type of population growth is represented by the above age pyramid?
Do you agree that regional and local variations exist within each.biome? Substantiate your answer with suitable example.
An orchid plant is growing on the branch of mango tree. How do you describe this interaction between the orchid and the mango tree?
In an association of two animal species, one is a termite which feeds on wood and the other is a protozoan Trichonympha present in the gut of the termite. What type of association they establish?
While living in and on the host species, the animal parasite has evolved certain adaptations. Describe these adaptations with examples.
If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (r) of the population?
