Organism and population

Ncert 12 biology Q n A

In a protected forest, it was observed that with you availability of unlimited food and absence of the predators the number of elephants have increased enormously. What type of growth is seen this

When resources in their habitat are unlimited, each species grows in number and reaches and normals population density in a short time this is called exponential growth

Exponential growth

When resources in their habitat are unlimited, each species grows in number and reaches and normals population density in a short time this is called exponential growth

Logistic growth

When the resources in the habitat are finite, it limits the growth of species

Verhulst-Pearl logistic Growth

A population growing and I habitat with limited resources shows initially a lag phase followed by phases of acceleration and deceleration and finally asymptote when the population density reaches the carrying capacity

Verhulst-Pearl logistic Growth Equation

dN/dt = rN(K - N/N)

Identify and explain the relationship between a fig tree and a wasp

Mutualism is the interaction between two living organisms where both organisms are equally benefited and no one is harmed. Fig tree inflorescence is pollinated by species wasp while searching for suitable egg laying sites and in return the fig offers the wasp some of its developing seeds as food for the developing wasp larvae.

List the adaptations of a kangaroo rat/ physiological adaptation

1. In the absence of external source of water, the kangaroo rat oxidises its internal fat to meet all its water requirements.

2. it has the ability to concentrated urine so that minimal volume of water is used to remove excretory products

Physiological adaptation in animals

Kangroo rat in the North America desert

Morphological adaptation

1. Plants in desert (opuntia)

2. Animals in cold climate

Morphological adaptation in animals / adaptations of animals in cold climate

1. Mammals from colder Climates generally have shorter years and limbs to minimise heat loss called as Allens rule.

2. Aquatic animals like seals have thick layer of fat called blubber below the skin that acts as an insulator to reduce loss of body heat.

Allen’s rule

Mammals from colder climates have shorter years and limbs to minimise heat loss

Which are the different types of adaptations observed in desert plants to minimise water loss

1. Thick cuticles on leave surfaces, Leaves are modified into spines (opuntia) and sunken stomata reduce transpiration.

2. Desert plants follow the crassulean acid metabolism photosynthetic pathway in which the stomata remains closed during daytime and open during night.

3. photosynthesis takes place in the flat green stem called phylloclade

Which are the various types of defences evolved in plants against herbivores

Plants evolved variety of morphological and chemical defences against herbivores

1. Thorns in acacia cactus (morphological)

2. Many plants produce and stores and chemicals which make the herbivore sick if eaten and even kill the predators. Calotropis is produces poisonous cardiac glucosides. Nicotine, caffeine, quinine, opium are produced against grazers and browsers.

Eurythermal

Organism which can tolerate and thrive and wide range of temperature

Birds mammals

Euryhaline

Organisms which can tolerate a wide range of salinity

Stenohaline

Organisms which can tolerate a narrow range of salinity

A gardener advised to grow calotropis plant for fencing his field give reason

The plant produces highly poisonous, cardiac glycosides, which will inhibit cattle or goats from browsing on the field if it is used as a fencing.

Explain how pseudocopulation by species of Bee ensures guaranteed will pollination in orchid ophrys

The Mediterranean orchid employs sexual deceit by making one of its flower petal bear an uncanny resemblance to the female bee in size, colour and marking the male bees attracted to what it perceives as a female pseudocopulate with it and during that process it is dusted with pollen from the flower. when the same the pseudocopulates with another flower, it transfers the pollen and pollinate the flower.

When a group of people went at a place for excursion at a high altitude, they experience, nausea, fatigue, and heart palpitations, predict the cause of it, and how did the bodies get acclimatised to this condition.

When a person moves to a higher altitude, the body develops altitude sickness because of the low atmospheric pressure as it does not get enough oxygen. The body compensates low oxygen availability by increasing red blood cell production, decreasing the binding capacity of haemoglobin and increasing breathing rate.

Mutualistic relationship examples

1. Fig tree and wasp

2. Orchid ophrys and Bee

Interference competition

The feeding efficiency of one species might be reduced due to the interfering and inhibitory presence of the other species

Competitive release

A species whose distribution is restricted to a small geographical area because of the presence of a competitively superior species which is found to expand its distribution range romantically when the competing species is experimentally removed.

Resource partitioning

If the species compete for the same resource, they could avoid competition by choosing for instance, different times for feeding or different foraging patterns

Gause’s Competitive exclusion principle

To closely related species competing for the same resource cannot coexist indefinitely and the competitively inferior one will be eliminated eventually.

Define the role of light as an abiotic factor in the environment

1. All autotrophs depend upon light as a source of energy for preparing food by photosynthesis and release oxygen.

2. Many plans also depend on sunlight to meet their photo periodic requirements for flowering

3. many animals to depend upon daily and seasonal variations in light intensity and duration as cues for timing, their foraging, reproductive and migratory activities.

4. The availability of light on land is closely linked with that of temperature. Since the sun is the source for both.

5. Energy source that sustains a deep ocean ecosystem is from chemical reactions. Different components of the visible spectrum are available for marine plants living at the depths of the ocean..

What is commensalism? illustrate with suitable example

The type of interaction in which one species is benefited and the other is neither harmed nor benefited.

Orchids growing as an epiphyte on mango branch and Barnacles growing on the back of the whale

Clown fishes living among stinging tentacles of sea anemone. the fish get protection from predators which day away from the stinging tentacles.

The egrets always forage close to where the cattle are grazing because as they move, stir up and flush out the vegetarian insects that otherwise might be difficult for the egrets to find and catch.

Prey species have evolved as defence to avoid predation. give examples of animals

Some species of insects and frogs are critically coloured to avoid being detected easily by the predator.

Monarch butterfly is highly distasteful to its predator because of the special chemical present in its body.

The crow bird does not build its own nest. It lays eggs in the nest of a sparrow. Identify the interaction

Brood parasitism is which the parasitic bird lays its eggs in the nest of its host and lets the host incubate them. The egg of the parasitic bird have evolved to resemble the host egg to reduce the chances of being detected.

Elephant trample and destroy small plants in their path. Identify the interaction.

Amensalism. The plants are harmed but the elephants are unaffected

Behavioural adaptation. (Desert lizard)

Desert lizards deal with high temperatures of the habitat by managing to keep their body temperature fairly constant by behaviour adaptation. They bask in the sun and absorb heat when their body temperature drops below the comfort zone and move into the shade when the ambient temperature starts rising. some species capable of burrowing into the soil to hide and escape from the above ground heat.

Salinity of water/salt concentration parts per thousand

Inland waters >5

Sea 30-35

Hypersaline lagoon >100

Freshwater animals cannot live for long and sea water. Give reason

Because of the osmotic problems arising due to high salinity

Homoeostasis

It is a response to abiotic factor to maintain the constancy of its internal environment. Despite varying external environmental conditions.

Regulation in birds and mammals

All birds and mammals, and a few lower vertebrates and invertebrates are capable of thermoregulation and Osmoregulation.

Mammals during summer Sweat profusely and evaporation brings down temperature of the body during winter. Shivering occurs which kind of exercise to produce heat and raise the body temperature.

Conformers

Animals and plants that cannot maintain a constant internal environment and their body temperature changes with the ambient temperature, osmotic concentration of the body fluids changes with that of the osmotic concentration of the ambient water in aquatic organism

Why are you small animals loose body heat faster/ very small animals are rarely found in polar regions

Small animals have a larger surface area relative to their volume. So they tend to lose body heat very fast. When it is cold outside they have to spend much energy to generate body heat.

Migration

Temporary movement from a stressful habitat to a more hospitable area and return when the stressful period is over

Describe suspend as response to abiotic factor

Under unfavourable conditions

1. Bacteria, fungus and lower plans, slow down the metabolic rate and form a thick walls force to overcome stressful condition

2. Higher plants, seeds and some reproductive structures serve as a means to tide over a period of success, the reduce their metabolic activity and undergo dormancy

3. Some animals fail to migrate. Avoid the stress by skipping in time by undergoing hibernation during winter.

4. some snails and fishes undergo aestivation to avoid summer related problems

5. Many zooplankton in lakes and ponds Enter diapause, which is a state of suspended development.

What is adaptation?

Adaptation is morphological, physiological, behavioural attribute of the organism to survive and reproduce in its habitat

Natality and mortality difference

Natality	Mortality
Number of deaths during a given period in the population that are added to the initial density	Number of deaths in the population during a given period

Immigration V/s Emigration

Immigration	Emigration
The number of individuals of the same species that have come into the habitat from elsewhere during the time period	Number of individuals of the population who left the habit that I have gone elsewhere during the time period .

2 factors that could cause decline in the population density

Mortality and emigration

How is the tiger census taken

Based on pug marks and fecal pellets

Organism thats breeds once in a lifetime

Pacific salmon fish, bamboo

predation

Organisms of higher trophic level feed on organisms of lower trophic level

Importance of predator/predator keeps prey population under control

They act as a passage of transfer of energy across trophic levels.

Maintain species diversity in a community by reducing the intensity of competition among competing prey species.

Prey species could achieve very high population density and cause ecosystem instability. The ability of predator is to regulate prey population.

Biological control methods adopted in agricultural pest control are based on the ability of the predator to regulate prey population

Mycorrhizae

Association between fungi and the roots of higher plants. Where the fungi helps the plant in absorption of essential nutrients from the soil. While plants in turn provide me with energy yielding carbohydrates.

Mutualism