Question:

List any three important characteristics of a population and explain.

Answer:

1. Size: This refers to the total number of individuals in the population. It is an important characteristic because it determines the amount of resources available to the population and the number of individuals that can be studied.

2. Distribution: This refers to the geographic location of the population. It is important because it can influence the availability of resources, the access to health care, and the potential for interbreeding.

3. Diversity: This refers to the genetic and phenotypic variation within the population. It is important because it increases the chances of survival in the face of changing environmental conditions and can also lead to increased adaptability.

Question:

List the attributes that populations but not individuals possess.

Answer:

1. Size
2. Density
3. Distribution
4. Growth rate
5. Age structure
6. Migration rate
7. Mortality rate
8. Reproductive rate
9. Genetic composition

Question:

Define the following terms and give one example for each: (a) Commensalism (b) Parasitism (c) Camouflage (d) Mutualism (e) Interspecific competition

Answer:

(a) Commensalism: A type of relationship between two species where one species benefits from the relationship while the other species is unaffected. Example: An epiphytic plant that grows on the branches of a tree.

(b) Parasitism: A type of relationship between two species where one species benefits from the relationship while the other species is harmed. Example: A tick that feeds on the blood of a mammal.

(c) Camouflage: A type of adaptation that helps an organism blend in with its environment, making it harder for predators to detect it. Example: A chameleon changing colors to match its surroundings.

(d) Mutualism: A type of relationship between two species where both species benefit from the relationship. Example: A bee pollinating a flower in exchange for nectar.

(e) Interspecific competition: A type of competition between two species for resources such as food, water, and territory. Example: Two species of birds competing for the same nesting site.

Question:

What is the ecological principle behind the biological control method of managing with pest insects?

Answer:

Step 1: Understand what biological control is. Biological control is the use of natural predators, parasites, or pathogens to reduce or eliminate populations of pest insects.

Step 2: Understand the ecological principle behind biological control. The ecological principle behind biological control is that it is a sustainable method of pest management that uses natural processes to keep pest populations in balance. This helps to maintain a healthy ecosystem and prevent damage to crops and other plants.

Question:

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.

Answer:

(a) Adaptations of Desert Plants and Animals: Desert plants and animals have adapted to the extreme climate of the desert. These adaptations include thick fur to protect against the sun and the heat, long roots to access water deep underground, and the ability to store water in their bodies. Animals such as the camel, kangaroo rat, and desert tortoise have also adapted to survive long periods without water.

(b) Adaptations of Plants to Water Scarcity: Plants have adapted to survive in water-scarce environments by developing deep roots to access water deep underground, thick waxy cuticles to reduce water loss, and small leaves to reduce the surface area exposed to the sun. They have also adapted to store water in their stems and leaves and to use water more efficiently.

(c) Behavioural Adaptations in Animals: Animals have adapted to survive in the desert by changing their behaviour. For example, some animals such as the kangaroo rat are nocturnal, which helps them avoid the heat of the day. Other animals such as the desert tortoise will dig burrows to escape the heat and conserve water.

(d) Importance of Light to Plants: Light is an essential part of photosynthesis, which is how plants make food. Without light, plants cannot survive. Plants have adapted to the desert environment by developing leaves that are small and covered in a waxy cuticle to reduce water loss. This also helps them to absorb more light.

(e) Effect of Temperature or Water Scarcity and the Adaptations of Animals: Animals have adapted to survive in extreme temperatures or water scarcity by changing their behaviour. For example, some animals such as the kangaroo rat are nocturnal, which helps them avoid the heat of the day. Other animals such as the desert tortoise will dig burrows to escape the heat and conserve water. They have also adapted to store water in their bodies and to use water more efficiently.

Question:

If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (r) of the population?

Answer:

Step 1: Understand the question. The question is asking for the intrinsic rate of increase (r) of a population that is growing exponentially and doubles in size in 3 years.

Step 2: Calculate the intrinsic rate of increase (r). The formula for calculating the intrinsic rate of increase (r) is r = ln(2)/t, where t is the time it takes for the population to double in size. In this case, t = 3 years. Therefore, r = ln(2)/3 = 0.231049.

Step 3: Answer the question. The intrinsic rate of increase (r) of the population is 0.231049.

Question:

How is diapause different from hibernation?

Answer:

Step 1: Understand what diapause and hibernation are.

Diapause is a period of suspended development in an animal’s life cycle, usually occurring in response to environmental conditions such as temperature, humidity, or food availability. Hibernation is a period of deep sleep during cold winter months in which an animal’s body temperature, heart rate, and breathing rate slow significantly.

Step 2: Compare the two.

Diapause and hibernation are both periods of suspended development in an animal’s life cycle, but they differ in terms of the environmental conditions that trigger them. Diapause is triggered by environmental conditions such as temperature, humidity, or food availability, while hibernation is triggered by cold winter temperatures. Additionally, hibernation is a period of deep sleep, while diapause is not necessarily a period of sleep.

Question:

Define phenotypic adaptation. Give one example.

Answer:

Answer: Phenotypic adaptation is the process by which an organism’s physical characteristics (phenotype) change over time in response to changes in the environment. An example of phenotypic adaptation is the development of thicker fur in Arctic foxes, which helps them to survive in the cold temperatures.

Question:

An orchid plant is growing on the branch of mango tree. How do you describe this interaction between the orchid and the mango tree?

Answer:

1. The orchid plant is using the mango tree as a support structure to grow.
2. The orchid is taking nutrients and water from the mango tree to sustain its growth.
3. The orchid is providing the mango tree with additional protection from the elements.
4. The orchid is benefiting from the shade and shelter provided by the mango tree.
5. The interaction between the two plants is an example of commensalism, where one organism benefits from the other without causing any harm.

Question:

Distinguish between the following: (a) Hibernation and Aestivation (b) Ectotherms and Endotherms

Answer:

a) Hibernation: Hibernation is a state of dormancy in which an animal’s metabolic rate slows down and it enters a state of deep sleep. It is usually seen in animals living in cold climates.

Aestivation: Aestivation is a state of dormancy in which an animal’s metabolic rate slows down and it enters a state of deep sleep. It is usually seen in animals living in hot climates.

b) Ectotherms: Ectotherms are animals that rely on external sources of heat to regulate their body temperature. They are also known as cold-blooded animals.

Endotherms: Endotherms are animals that can generate their own body heat and regulate their temperature internally. They are also known as warm-blooded animals.

Question:

Most living organisms cannot survive at temperature above 45oC. How are some microbes able to live in habitats with temperatures exceeding 100oC?

Answer:

1. First, it is important to understand that living organisms are made up of biological molecules that have evolved to function within certain temperature ranges.

2. Microbes, such as certain bacteria and archaea, have adapted to survive in extreme temperatures by producing proteins and enzymes that are able to function at higher temperatures.

3. These proteins and enzymes are able to withstand the higher temperatures, allowing the microbes to survive in habitats with temperatures exceeding 100oC.

4. Additionally, some microbes have adapted to survive by forming protective layers of proteins or polysaccharides around themselves, which help to insulate them from the extreme temperatures.

5. Finally, some microbes have evolved to produce heat-shock proteins, which help protect them from the effects of extreme temperatures.

Question:

With the help of suitable diagram describe the logistic population growth curve.

Answer:

Step 1: Draw a graph with the x-axis representing time and the y-axis representing population.

Step 2: Label the graph with the appropriate titles.

Step 3: Plot the points on the graph that represent the logistic population growth curve.

Step 4: Connect the points with a smooth curve.

Step 5: Label the curve with the appropriate title.

Question:

Define population and community.

Answer:

Step 1: Population is a group of individuals of the same species living in the same area at the same time.

Step 2: Community is a group of populations of different species living in the same area and interacting with each other.

Question:

List the various abiotic environmental factors.

Answer:

1. Temperature
2. Light
3. Soil
4. Air
5. Water
6. Minerals
7. Rocks
8. pH
9. Humidity
10. Wind

Question:

Give an example for: (a) An endothermic animal (b) An ectothermic animal (c) An organism of benthic zone

Answer:

(a) An endothermic animal: Human

(b) An ectothermic animal: Turtle

(c) An organism of benthic zone: Sea cucumber

Question:

Name important defence mechanisms in plants against herbivory.

Answer:

1. Thorns and Spines: These are sharp structures that protrude from the plant and can deter herbivores from eating the plant.

2. Toxins and Secondary Metabolites: Many plants produce toxins and secondary metabolites that are poisonous or distasteful to herbivores and can deter them from eating the plant.

3. Chemical Defenses: Some plants produce chemicals that can repel or deter herbivores from eating the plant.

4. Physical Barriers: Some plants have physical barriers such as waxy coatings or thick cuticles that can make it difficult for herbivores to access the plant.

5. Mimicry: Some plants have evolved to mimic other plants that are toxic or distasteful to herbivores, which can deter them from eating the plant.

6. Allelopathy: Some plants can produce chemicals that can inhibit the growth of other plants, which can make it difficult for herbivores to find food.

Question:

Select the statement which explains best parasitism. (a) One organism is benefited. (b) Both the organisms are benefited. (c) One organism is benefited, other is not affected. (d) One organism is benefited, other is affected.

Answer:

Answer: (d) One organism is benefited, other is affected.

Question:

If a marine fish is placed in a fresh water aquarium, will the fish be able to survive? Why or why not?

Answer:

1. No, a marine fish will not be able to survive in a fresh water aquarium because the salinity of the water in the aquarium is much lower than the salinity of the ocean water that a marine fish is used to living in.

2. Marine fish require a certain level of salt in the water in order to survive, and the fresh water aquarium will not provide this. Furthermore, the sudden change in salinity can be very stressful for a marine fish, leading to health complications and even death.