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The correct option is (b) Biological interaction

Best EXPLANATION: The INTERACTIONS between organisms in a COMMUNITY are called biological interaction. They may include organisms of the same SPECIES or DIFFERENT species. The interactions between organisms are essential for survival and the proper functioning of the ecosystem.

The CORRECT option is (a) Community

For explanation I would SAY: A group of populations is known as a community. It is a group of people who share the same place or live WITHIN the same area. These people may share COMMON characteristics. It is the organizational LEVEL between population and ecosystems.

The correct CHOICE is (d) Psammophytes

Easiest explanation: The PLANTS adapted to LIVE in the sand are called psammophytes. They have an adventitious root system. They are also found along seas, SANDS along rivers and large lakes where sand is AVAILABLE.

The correct ANSWER is (b) Xerophytes

To EXPLAIN I would say: The MECHANICAL TISSUE that is COLLENCHYMA is best developed in xerophytes. These are enclosed within rigid channels to avoid water loss. Along with this bark of xerophytes is also well developed to retain water.

Right choice is (C) KANGAROO RAT

To elaborate: Solid URINE is excreted by kangaroo rat to avoid excess loss of water. They are rodents and their KIDNEYS have developed mechanisms to highly concentrate their urine. They have longer papilla in their kidneys.

The correct answer is (b) Modified stems

The best EXPLANATION: In xerophytes, there is an ADAPTION in which PHOTOSYNTHESIS occurs with the help of modified stems to avoid water loss. Roots of xerophytes help in the storage of water. Scaly LEAVES do not help MUCH in photosynthesis.

Correct choice is (c) Xerophytes

The BEST explanation: Sunken stomata are a FEATURE of xerophytes. It is an adaptation made by desert or ICY area PLANTS to avoid water loss. Some examples of xerophytes are some Gymnosperm plants, cacti, pineapple, ETC.

The correct choice is (d) Desert

The best I can explain: The succulents are USUALLY SEEN in desert areas. These are thick, fleshy and retain water in arid conditions. They are DROUGHT resistant, follow CRASSULACEAN ACID metabolism (CAM) pathway and store water in leaves and stems.

The correct option is (c) AESTIVATION

For explanation: The poikilotherms use aestivation as a protective mechanism against EXTREME HEAT. The suspension of metabolic activities during summer is called aestivation. It helps in maintaining body temperature and avoids water LOSS in mostly cold-blooded animals such as snails, bees, tortoise, crocodile, etc.

The correct choice is (d) SUCCULENTS

Easy explanation: The stomata OPEN during the night in succulents. These plants show an inverted stomatal RHYTHM as COMPARED to normal plants. The succulents are usually seen in desert areas. To reduce transpiration these plants secrete WAXES or resins.

Correct ANSWER is (c) Desert lizard has the ability to keep the constant body temperature

To elaborate: Among the above-given sentences, the desert lizard has the ability to keep a constant body temperature is an incorrect STATEMENT. This is so because lizards are ECTOTHERMS, cold-blooded WHOSE temperature CHANGES as per the temperature of surroundings.

Correct OPTION is (d) INCREASING red BLOOD cell formation

The explanation is: The body COMPENSATES for LOW oxygen availability in altitude sickness by increasing red blood cell formation that will increase the uptake of oxygen. A person experiences altitude sickness >3500 m or >8,000 feet.

The correct answer is (B) Heart palpitations

Easy explanation: AMONG the above-given options heart palpitation is a symptom of altitude SICKNESS. It occurs due to a decrease in pressure around a person due to which there is a decrease in OXYGEN level. Some other SYMPTOMS are nausea, fatigue, etc.

The correct option is (a) >3500 m

The explanation is: A person experiences altitude sickness >3500 m or >8,000 feet. It is ALSO KNOWN as MOUNTAIN sickness. It occurs due to a decrease in pressure around a person due to which there is a decrease in oxygen level.

Right choice is (b) Adaptation

To elaborate: Any attribute of the organism that enables the organism to SURVIVE and reproduce in its HABITAT called adaptation. It is an evolutionary PROCESS that takes place from generation to generation. It involves a CHARACTER or feature or trait that helps an organism in a given habitat.

The correct CHOICE is (c) DEATH

Easiest explanation: The ORGANISMS stop their metabolic activities completely after death. In all others such as hibernation, AESTIVATION, DIAPAUSE the metabolic activities of organisms are slowed temporarily to avoid the loss of energy.

Right answer is (d) Keoladeo National PARK, RAJASTHAN

Easiest explanation: Many birds from Siberia migrate to Keoladeo National Park, BHARATPUR, Rajasthan. These Siberian cranes usually migrate during the ONSET of the autumn SEASON and then return to arctic tundra for breeding around the end of April and the beginning of May.

Correct choice is (d) They bask in the sun

To EXPLAIN I would say: The desert lizards are cold-blooded animals that cannot REGULATE their body TEMPERATURE. They bask in the sun when their body temperature drops to regulate their temperature to perform various metabolic activities.

Right option is (c) ALLEN’s rule

To elaborate: Allen’s rule is an eco-geographical rule which states that in a cold climate, mammals possess shorter EARS and limbs to minimize HEAT loss.It was stated by Joel Asaph Allen in 1877. It is a FORM of an ADAPTATION done for survival in colder regions.

Right choice is (c) Thermoconformers

Explanation: Thermoconformers are the ORGANISMS whose body temperature changes according to changing environmental TEMPERATURES. They do not carry out THERMOREGULATION. They are usually cold-blooded ANIMALS.

The correct CHOICE is (d) Thermoregulators and osmoregulators

Explanation: All mammals and birds are thermoregulators and osmoregulators. These are the organisms the ORGANISM in which body temperature and the osmotic concentration of the body fluid CHANGES with the ambient temperature and change with that of the ambient water osmotic concentration RESPECTIVELY.

The correct OPTION is (B) Homeostasis

To elaborate: Homeostasis is MAINTAINING the constancy of the INTERNAL environment according to changing the EXTERNAL environment. It is a self-regulating process done by all organisms.

Right OPTION is (a) Aestivation

Explanation: The suspension of metabolic activities during summer is CALLED aestivation. It is prolonged dormancy and is also known as summer sleep. It HELPS in maintaining body temperature and avoids water loss in mostly cold-blooded animals such as snails, bees, TORTOISE, crocodile, ETC.

The correct choice is (b) Stage of suspended development

Best explanation: DIAPAUSE is a stage of suspended development. It is LIKE hibernation in HIGHER animals EXCEPT it is used to avoid hot, dry summers in tropical AREAS. It is done by the zooplankton species in lakes and ponds under unfavorable conditions.

Correct answer is (d) Aestivation

For explanation I would say: Some snails and fishes enter in aestivation during SUMMERS. It is prolonged dormancy and is also known as summer sleep. It helps in MAINTAINING body temperature and AVOIDS water loss in MOSTLY cold-blooded animals such as earthworms, BEES, tortoise, crocodile, etc.

Right option is (b) DORMANCY

The explanation is: The seeds ENTER dormancy under unfavorable conditions. It is an adaptive mechanism of PLANTS which prevents seed from GERMINATING. It helps in delayed germination under FAVORABLE conditions.

Correct option is (c) PERIODIC

Easy explanation: Hibernation is a stage of suspended development seen in higher ORGANISMS. It occurs in winters. It is MOSTLY seen in endotherms in which all the METABOLIC activities are SLOWED down. It is a periodic cycle.

Correct CHOICE is (B) Surface area

Explanation: The GAIN or LOSS of heat occurs through the surface area of the body. It is important for maintaining homeostasis of an ORGANISM. It is easily done by mammals as they are thermoregulators.

Correct choice is (a) Diapause

For explanation: The zooplankton species in lakes and ponds enter diapause STAGE under unfavorable conditions. Diapause is a stage of suspended DEVELOPMENT. It is LIKE hibernation in higher ANIMALS except it is used to avoid hot, dry summers in TROPICAL areas.

Right option is (d) SEED

For explanation: SEEDS in higher PLANTS serve as a means to tide over a period of stress and also helping in dispersal. A seed is an embryonic plant, a viable offspring that is ENCLOSED in the PROTECTIVE outer covering.

The correct ANSWER is (b) Fungi

The explanation: Fungi produce various KINDS of thick-walled spores that help to survive unfavorable conditions and GERMINATE on the availability of a SUITABLE environment. Along with these such spores are ALSO produced by bacteria, lower plants, and algae.

Right ANSWER is (C) HUMMING birds

Explanation: Thermoregulation is energetically expensive to humming birds because of their small size. The smaller is the ANIMALS; more is the HEAT loss from the body. Thermoregulation is energetically expensive for small animals and shrews.

The CORRECT option is (d) Constant body TEMPERATURE

Explanation: According to EVOLUTIONARY biologists mammals are successful because they have the ability to maintain constant body temperature. They are warm-blooded animals and also called as ENDOTHERMS or regulators.

The correct answer is (B) All mammals

The EXPLANATION: All mammals are capable of thermoregulation and osmoregulation. Thermoregulation is the ability to maintain constant BODY temperature under changing environmental temperatures while osmoregulation is the ability to maintain a constant osmotic CONCENTRATION of body fluids under HIGH solute concentrations.

The correct option is (a) REGULATORS

Easy explanation: The warm-blooded animals are those who are ABLE to maintain homeostasis by physiological (SOMETIMES BEHAVIORAL also) MEANS which ensure constant body temperature, constant osmotic concentration, etc. They are also called as regulators. Some examples are mammals, birds, etc.

Correct option is (b) Conformers

Easy explanation: Conformers are the poikilotherms that are the organisms in which body TEMPERATURE changes with the ambient temperature and in AQUATIC animals, the osmotic concentration of the body FLUID CHANGE with that of the ambient water osmotic concentration. Some examples are Insects, lizards, FISHES, etc.

Correct answer is (d) Aphotic

The EXPLANATION: The region in the LAKE present below photic is aphotic. It is present DEEP within the lake and light cannot penetrate through it. It lies between the photic and BENTHIC region of the lake.

Right choice is (d) Benthic

The explanation: The light cannot penetrate the BOTTOM zone of the LAKE called benthic. Littoral is the SHALLOW, coastal region. Limnetic is very deep and has open water while PHOTIC is the UPPER part of limnetic. Light can pass through all three zones except benthic.

Correct answer is (c) HUMUS

The explanation is: Humus is a component of SOIL. A good soil consists of approximately 10% humus. Along with this it also consists of 40% minerals, 25% soil air, 25% WATER which also helps in the growth of microflora and FAUNA.

Correct answer is (c) Minerals

Best explanation: A good soil PROVIDES minerals, water and support to plants. The TOP LAYER is known as the FEEDING zone since the nutrients required by plants are present there. It also HELPS in maintaining pH.

Right choice is (d) Motion in air

For explanation I would say: Wind is the motion in the air. A number of physical, ANATOMICAL and physiological changes of plants are AFFECTED by wind. It is RESPONSIBLE for the acceleration in the rate of transpiration which may LEAD to DESICCATION in plants.