Untitled Quiz

Movement and Life

• Visible movements, like a cat running, are associated with life because they often indicate a response to changes in the environment.
• Living organisms use changes in their environment to their advantage by adapting and evolving.
• Movements in response to the environment are carefully controlled to ensure survival.

Control and Coordination in Living Organisms

• Living organisms must use systems for control and coordination to regulate their internal environment and respond to external stimuli.
• In animals, the nervous system controls and coordinates functions of the body.

The Nervous System

• The nervous system detects changes in the environment through specialized sensory organs.
• Stimuli are detected and sent to the cell body as electrical impulses.
• Electrical impulses trigger chemical reactions at the synapse, allowing for communication between neurons.

Reflex Actions

• A reflex action is an automatic, involuntary response to a stimulus.
• Reflex actions are important for quick responses to dangerous situations, like touching a flame.
• A reflex arc is the pathway followed by a nerve impulse during a reflex action.
• The reflex arc connection occurs in the spinal cord, without the brain's involvement.

Importance of Reflex Actions

• Animals need reflex actions for quick responses to danger, even without conscious thought.
• While animals have complex neuron networks, reflex actions are still essential for survival.

The Central Nervous System

• The spinal cord is responsible for relaying information between the brain and the rest of the body.
• The human brain is responsible for thought, memory, learning, and controlling voluntary movements.
• Voluntary actions are those that are consciously controlled by the brain.
• The brain and the spinal cord make up the central nervous system (CNS).

The Peripheral Nervous System

• The peripheral nervous system (PNS) connects the CNS to the rest of the body.

Parts of the Brain

• The brain has three main parts: the forebrain, the midbrain, and the hindbrain.
• The forebrain is responsible for higher functions like thinking, learning, and memory.
• The hunger center is located in the forebrain.
• The medulla, part of the hindbrain, controls involuntary functions like breathing and heartbeat.
• The cerebellum is responsible for coordination and balance.

Protection of the Nervous System

• The brain is protected by the skull.
• The spinal cord is protected by the vertebral column.

How the Nervous System Works

• The nervous tissue sends signals through electrical impulses, causing actions or movements.
• Muscle cells change their shape in response to these signals.

Differences in Movement

• A reflex action is an automatic response, while walking is a voluntary movement controlled by the brain.
• At the synapse between two neurons, chemical messengers called neurotransmitters transmit signals.

Sensory Perception

• The smell of an agarbatti is detected by olfactory receptors in the nose, sending signals to the brain through the olfactory nerve.

Maintaining Balance

• The cerebellum maintains posture and equilibrium of the body.

Plant Control and Coordination

• Plants don't have a nervous system like animals.
• Plant movements are primarily controlled by growth hormones and external stimuli.
• The movement of a chhui-mui leaf in response to touch is caused by changes in water pressure within cells, not growth.
• The movement of a pea plant around a support is an example of growth-dependent movement.

Plant Responses to Stimuli

• The sensitive plant detects touch through specialized cells in its leaves.
• The cells in the leaves of the sensitive plant lose water, causing the leaves to fold up.
• The two main types of plant movement are tropism (growth towards or away from a stimulus) and nastic movements (non-directional movements).

Plant Hormones

• Shoots grow towards light (phototropism), ensuring access to sunlight for photosynthesis.
• Roots grow away from light (negative phototropism), seeking water and nutrients.
• Geotropism is the growth of plants in response to gravity.
• Plants communicate information through chemical messengers called plant hormones (phytohormones).
• Some plants respond quickly to touch due to rapid changes in water pressure, while others grow slowly in response to light or gravity.

Examples of Plant Hormones

• Auxins are plant hormones that promote growth.
• Auxins help tendrils grow around a support by promoting unequal growth on the side opposite the touch, causing the tendril to bend.

Hydrotropism

• To demonstrate hydrotropism, plant two identical seeds in separate pots with different water levels: one pot dry and one pot wet.
• The plant in the wet pot should grow its roots towards the water source.

Hormonal Communication in Animals

• Animals also use chemical, or hormonal, means of information transmission.
• Squirrels experience a complex, coordinated response to fear, involving adrenaline and other hormones.
• Adrenaline is a hormone that prepares the body for "fight or flight" response, increasing heart rate and breathing, and diverting blood flow to muscles.

Role of Hormones in Growth and Regulation

• Hormones play significant roles in regulating growth and development in animals.
• Hormones have specific functions, acting on target cells and tissues.
• The pancreas is responsible for producing insulin, a hormone regulating blood sugar levels.

Diabetes

• Patients with diabetes may require insulin injections to regulate their blood sugar levels.

Nutrition in Living Organisms

• Autotrophic organisms, like plants, can produce their own food through photosynthesis.
• Heterotrophic organisms, like animals, obtain food from other sources.

Comparing Nervous System and Hormones

• The nervous system provides rapid communication and short-term responses.
• Hormones provide slower but long-lasting responses, often affecting the body's overall growth and development.

Excretion

• Nephrons in the kidneys filter waste products from the blood, producing urine.
• The amount of urine produced is regulated by hormonal control.
• Plants get rid of excretory products through diffusion or by releasing them into the soil.

Reproduction

• Pollination is the transfer of pollen from the anther to the stigma.
• Fertilization is the fusion of the male gamete (sperm) with the female gamete (egg).
• The seminal vesicles and the prostate gland secrete fluids that contribute to semen.

Puberty

• Puberty is a period of rapid physical and hormonal changes that occur in boys and girls leading to sexual maturity.
• Girls experience changes like breast development, menstruation, and widening of hips.

Embryo Development and Protection

• The embryo receives nourishment from the mother's body through the placenta.
• A copper-T is a contraceptive device that prevents pregnancy but doesn't protect against sexually transmitted diseases.