Mix Examples - Control and Coordination Questions in English

(A) The statement is True.
In the human brain,the midbrain and hindbrain (specifically the medulla oblongata) are responsible for regulating various involuntary actions.
For example,the medulla in the hindbrain controls involuntary activities such as blood pressure,salivation,and vomiting.
The midbrain is involved in relaying sensory information and controlling involuntary eye movements and auditory reflexes.

(A) The statement is True.
The human brain is divided into three main parts: the forebrain,midbrain,and hindbrain.
The hindbrain consists of the pons,medulla oblongata,and cerebellum.
Therefore,the cerebellum is indeed a part of the hindbrain.

(FALSE) The statement is False.
Blood pressure,salivation,and vomiting are involuntary actions known as reflex actions or autonomic functions.
These involuntary activities are controlled by the medulla oblongata,which is a part of the hindbrain,not the cerebrum.

(FALSE) The statement is False. The part of the brain responsible for maintaining the posture and balance of the body is the cerebellum,which is a part of the hindbrain,not the forebrain.

(FALSE) The statement is False. Insulin is a hormone produced by the pancreas that helps regulate blood glucose levels. Instead of raising it,insulin lowers the blood sugar level by facilitating the uptake of glucose into cells for energy production or storage as glycogen in the liver and muscles.

(FALSE) The statement is False.
Goitre is caused by the deficiency of iodine in the diet,not calcium.
Iodine is essential for the synthesis of the thyroid hormone,thyroxine,by the thyroid gland.
Calcium deficiency typically leads to issues related to bone health,such as osteoporosis or rickets.

(FALSE) The statement is False. Goitre is a condition characterized by the enlargement of the thyroid gland,which is located in the neck region. Therefore,the swelling associated with goitre occurs in the neck,not the abdomen.

(TRUE) The statement is True. The pituitary gland,often referred to as the master gland,is located at the base of the brain. It secretes several hormones,including the growth hormone $(GH)$,which is essential for the growth and development of bones and tissues in the body.

(A) The statement is True. Abscisic acid $(ABA)$ is a plant hormone known as a growth inhibitor. It promotes seed dormancy,induces leaf senescence,and causes the closure of stomata to prevent water loss during stress conditions,thereby inhibiting overall plant growth.

(A) The statement is True.
Growth of pollen tubes towards the ovules is a classic example of chemotropism.
Chemotropism is the movement or growth of a plant part in response to a chemical stimulus.
In this process,the ovule releases specific chemical substances that guide the pollen tube to grow towards it,ensuring successful fertilization.

(B) The movement of a plant part in response to gravity is known as $Geotropism$ (also called $Gravitropism$).
Roots typically show positive $Geotropism$ as they grow downwards towards the pull of gravity,while shoots show negative $Geotropism$ as they grow upwards away from it.

(A) Phototropism is the growth of an organism in response to a light stimulus.
Positive phototropism is growth towards the light source,which is typically observed in the shoot or stem of a plant.
Negative phototropism is growth away from the light source.
Roots exhibit negative phototropism because they grow away from light and towards gravity (geotropism).

(D) The growth of the pollen tube towards the ovule is a classic example of $Chemotropism$.
This occurs because the ovule releases specific chemical substances that act as a signal for the pollen tube.
The pollen tube senses these chemicals and grows in the direction of the higher concentration of these substances,which leads it directly to the ovule for fertilization.

(B) The movement of a plant part in response to light is known as phototropism.
When the shoot of a plant grows towards a light source,it is called positive phototropism.
Geotropism is the response to gravity,thigmotropism is the response to touch,and photonasty is a non-directional movement in response to light.

(A) Thigmotropism is the directional growth movement of a plant in response to a touch stimulus or physical contact with a solid object.
For example,tendrils of climbing plants coil around a support when they come into contact with it.
Therefore,the correct stimulus for thigmotropism is touch.

(B) The $Cerebellum$ is a part of the hindbrain located at the back of the skull. Its primary function is to coordinate voluntary muscle movements and maintain the posture and balance of the body. It ensures that movements are smooth and precise.

(B) The human spinal cord gives rise to $31$ pairs of spinal nerves.
These nerves are categorized based on the region of the vertebral column from which they emerge:
$8$ pairs of cervical nerves,
$12$ pairs of thoracic nerves,
$5$ pairs of lumbar nerves,
$5$ pairs of sacral nerves,and
$1$ pair of coccygeal nerves.
Therefore,the total number of pairs is $8 + 12 + 5 + 5 + 1 = 31$ pairs.

(B) The human brain is divided into three main parts: the forebrain,midbrain,and hindbrain.
$1$. The forebrain consists of the cerebrum,thalamus,and hypothalamus.
$2$. The midbrain connects the forebrain to the hindbrain.
$3$. The hindbrain consists of three main structures: the cerebellum,the pons,and the medulla oblongata.
Therefore,the cerebellum,medulla,and pons are parts of the hindbrain.

(C) Iodine is an essential mineral required for the synthesis of the hormone $Thyroxine$ in the thyroid gland.
$Thyroxine$ regulates the metabolism of carbohydrates,proteins,and fats in the body.
$A$ deficiency of iodine in the diet leads to a condition known as goitre,which is characterized by the swelling of the thyroid gland.

(A) The correct answer is $A$.
Adrenaline is a hormone secreted by the adrenal glands,which are located on top of the kidneys,not by the pituitary gland.
The pituitary gland secretes hormones like growth hormone,$TSH$,and $ACTH$.
Estrogen and progesterone are female sex hormones produced by the ovaries.
Insulin is a hormone produced by the pancreas to regulate blood glucose levels.

(C) The spinal cord is a long,thin,tubular structure made of nervous tissue that extends from the medulla oblongata in the brainstem and continues down the vertebral column. The medulla oblongata is the lowest part of the brain and serves as the transition point between the brain and the spinal cord.

(C) The hormone $Adrenaline$ is secreted by the adrenal glands in response to stress or emergency situations.
It is often called the 'fight-or-flight' hormone.
When released into the blood,it increases heart rate,breathing rate,and blood pressure,and diverts blood flow to muscles,preparing the body to react quickly to danger.

(C) The male sex hormone is $Testosterone$.
It is primarily produced in the testes of males.
$Testosterone$ is responsible for the development of secondary sexual characteristics in males,such as deepening of the voice,growth of facial and body hair,and muscle development.
$Estrogen$ and $Progesterone$ are female sex hormones,while $Adrenaline$ is a stress hormone produced by the adrenal glands.

(B) In the human body,endocrine glands can be either paired or unpaired.
$1$. Adrenal glands are paired,located on top of each kidney.
$2$. Testes are the primary sex organs in males and occur as a pair.
$3$. Ovaries are the primary sex organs in females and occur as a pair.
$4$. The Pituitary gland is a small,pea-sized gland located at the base of the brain and is a single,unpaired structure.
Therefore,the correct answer is $B$ (Pituitary).

(C) Living organisms respond to stimuli in their environment. In animals,this response is typically manifested as movement. For example,when we touch a hot object,we move our hand away. This movement is a result of the coordination between the nervous system and the muscular system.

(D) Thigmonasty is a type of nastic movement in plants that occurs in response to touch or mechanical stimulation.
For example, the folding of leaves in the sensitive plant $(Mimosa \text{ pudica})$ when touched is a classic example of thigmonasty.
Since the original options provided did not include 'touch', the correct answer is 'touch'.
Gravity-related movement is geotropism, water-related is hydrotropism, and light-related is phototropism or photonasty.

(D) In animals, the $Nervous$ $system$ and the $Endocrine$ $system$ work together to achieve coordination and regulation.
The $Nervous$ $system$ provides quick, electrical signals for rapid responses, while the $Endocrine$ $system$ uses chemical messengers called hormones to provide slower, long-lasting regulation of physiological processes.
Together, they ensure that the body functions as an integrated unit.

(A) Plants lack a specialized nervous system and sensory organs,which are present in animals to process and respond to complex stimuli. While plants do produce hormones (phytohormones) to regulate growth and development,their response to external stimuli is primarily chemical and slower compared to the rapid electrical signaling found in animal nervous systems. Therefore,the absence of a nervous system is the primary reason for their limited response.

(A) Plant hormones are classified into two categories: growth promoters and growth inhibitors.
$1$. Growth promoters include Auxins,Gibberellins,and Cytokinins,which stimulate cell division,cell enlargement,and growth.
$2$. Growth inhibitors include Abscisic acid,which inhibits growth and promotes dormancy.
$3$. Ethylene acts primarily as a growth inhibitor,though it has complex roles in ripening.
$4$. Insulin is a hormone found in animals,not plants.
Therefore,Auxin is the correct answer as it is a well-known plant growth promoter.

(C) Plant hormones are chemical substances that regulate growth and development.
$Auxin$,$Gibberellin$,and $Cytokinin$ are primarily known as plant growth promoters.
$Abscisic$ $acid$ $(ABA)$ is known as a plant growth inhibitor.
It promotes dormancy in seeds,induces leaf abscission,and helps the plant withstand stress conditions by closing stomata.

(B) Sensitive plants,such as $Mimosa$ $pudica$ (touch-me-not),respond to touch through a mechanism involving changes in the amount of water in their cells.
When touched,the plant cells at the base of the leaflets lose water,which leads to a loss of turgor pressure.
This change in turgor pressure causes the leaves to fold or droop.
This movement is independent of growth and is regulated by the movement of water,which is a type of plant movement known as thigmonasty.
Since plants do not possess nervous or muscular tissues,they rely on chemical and physical changes (like water movement) to respond to stimuli.

(A) When the growth movement of a plant part is towards the stimulus, it is known as $Positive \ tropism$.
Conversely, if the growth movement is away from the stimulus, it is known as $Negative \ tropism$.
$Geotropism$ refers specifically to growth in response to gravity, and $Chemotropism$ refers to growth in response to chemical stimuli.
Therefore, the general term for growth towards a stimulus is $Positive \ tropism$.

(C) The movement of a plant part in response to light is known as $Phototropism$.
Since sunflowers track the movement of the sun throughout the day, their growth and orientation are influenced by light, which is a classic example of $Phototropism$.
$Hydrotropism$ is the response to water, $Geotropism$ is the response to gravity, and $Chemotropism$ is the response to chemical stimuli.

(B) Tropism is the growth or movement of a plant part in response to an external stimulus.
Hydrotropism is the growth or turning of plant roots towards or away from moisture or water.
Since the roots grow towards the water, this movement is known as $Positive \ hydrotropism$.

(A) Plant tendrils exhibit $Thigmotropism$.
$Thigmotropism$ is the directional growth movement of a plant part in response to touch or physical contact with a solid object.
When tendrils come in contact with a support,the side in contact with the object grows slower than the side away from it,causing the tendril to coil around the support.

(C) When a potted plant is placed horizontally,the stem exhibits negative geotropism (or negative gravitropism).
This means the stem grows away from the pull of gravity.
Due to the redistribution of auxin,which accumulates on the lower side of the stem,the cells on the lower side grow faster than those on the upper side.
As a result,the stem bends and grows upwards,away from the ground.

(D) The shoot of a plant exhibits positive phototropism because it grows towards the light source.
It also exhibits negative geotropism (or negative gravitropism) because it grows away from the pull of gravity (upwards against the gravitational force).
Therefore,the correct combination is positive phototropism and negative geotropism.

(B) Phototropism is the growth of an organism in response to a light stimulus.
Positive phototropism is growth towards the light source,which is observed in the stem of the plant.
Negative phototropism is growth away from the light source.
The roots of a plant exhibit negative phototropism because they grow away from light and towards the soil (geotropism).

(A) Photonastic movement is a type of nastic movement in plants where the movement of plant parts,such as the opening and closing of flowers,occurs in response to changes in light intensity.
Jasmine $(Jasminum)$ flowers exhibit photonastic movement,as they typically open in response to the light conditions of the evening or night.
Sunflower exhibits heliotropism (solar tracking),not photonasty.
Therefore,the correct option is $A$.

(C) The movement shown by $Mimosa$ $pudica$ (touch-me-not plant) in response to touch is known as thigmonasty or seismonasty.
This is a non-directional movement where the plant leaves fold inward upon being touched.
Unlike tropisms,which are directional growth movements,thigmonastic movements are independent of the direction of the stimulus.
Therefore,the correct option is $C$.

(C) The movement of a plant part in response to light is known as $phototropism$.
Sunflower flowers exhibit a directional growth movement towards the Sun,which is a classic example of $phototropism$.
$Chemotropism$ is movement in response to chemicals.
$Hydrotropism$ is movement in response to water.
$Photonasty$ is a non-directional movement in response to light,which is not the case for the directional tracking of the Sun by sunflowers.

(C) The movement of plant parts in response to temperature is known as $Thermonasty$.
$Photonasty$ is the movement in response to light.
$Thigmonasty$ is the movement in response to touch.
$Tropism$ is a directional growth movement in response to a stimulus.

(A) The opening of a lotus flower in response to light is known as $Photonasty$.
$Photonasty$ is a nastic movement in which a plant part moves in response to light intensity.
Since the lotus flower opens in the morning due to the presence of sunlight,it is a classic example of $Photonasty$.

(A) The opening of a tulip flower is a response to changes in temperature.
When the temperature rises,the flower opens,and when the temperature drops,it closes.
This type of non-directional movement in plants in response to temperature is known as $Thermonasty$.

(A) The neuron consists of three main parts: the cell body (cyton),dendrites,and the axon.
$1$. The cell body contains the nucleus and cytoplasm.
$2$. Dendrites are the short,branched fibers that project out from the cell body.
$3$. These fibers receive impulses and transmit them towards the cell body.
$4$. Therefore,the small fibers on the cell body are known as dendrites.

(B) The myelin sheath is an electrically insulating layer that surrounds the axons of many neurons.
It is primarily composed of lipids (fats) and proteins.
Specifically, the myelin sheath consists of approximately $70-80\%$ lipids and $20-30\%$ proteins by dry weight.
These components provide the necessary insulation to increase the speed of electrical impulses along the nerve fibers.

(B) The gap between two neurons is known as a $Synapse$.
At the $Synapse$,electrical signals are converted into chemicals that can cross over to the next neuron and be converted back into electrical signals.

(B) neuron consists of three main parts: the cell body (cyton),dendrites,and the axon.
$1$. Dendrites are the branched,tree-like structures that extend from the cell body.
$2$. They are specialized to receive electrical impulses or chemical signals from sensory receptors or other neurons.
$3$. These signals are then transmitted towards the cell body and subsequently down the axon.
Therefore,the correct part that receives messages is the dendrite.

(A) The human nervous system is divided into two main parts: the Central Nervous System $(CNS)$ and the Peripheral Nervous System $(PNS)$.
The Central Nervous System $(CNS)$ acts as the main processing center for the entire nervous system.
It consists of two primary organs: the brain and the spinal cord.
The brain is the control center for all bodily functions,while the spinal cord acts as a pathway for signals between the brain and the rest of the body.

(B) The average weight of an adult human brain is approximately $1300 \text{ g}$ to $1400 \text{ g}$.
Among the given options, $1350 \text{ g}$ is the most accurate representation of the average weight of an adult human brain.