- Plants remove oxygen as a waste product during photosynthesis and get rid of excess water through transpiration.
- Some wastes are stored in vacuoles, old leaves, or shed parts like leaves and bark.
- Plants also store waste as resins and gums in old xylem or release waste into the soil through roots.
Definitions [17]
Definition: Transpiration
The loss of water vapour from the aerial parts of a plant, mainly through stomata, is called transpiration.
Definition: Translocation
The movement of soluble products of photosynthesis from the leaves to other parts of the plant through phloem is called translocation.
Define excretion.
Excretion is the process that biological organisms use to expel or eliminate the waste products produced by their metabolism.
Define the following term:
Osmoregulation
The kidney while removing wastes like urea from the blood also regulates its composition, i.e., the percentage of water and salts. This function is called osmoregulation.
Define the following term:
Micturition
Micturition is the process of expelling urine out of the body through the urethra by opening the sphincter muscles and passing urine, involving the relaxation of the sphincter muscles between the urinary bladder and urethra.
Definition: Excretion
The process of removal of chemical wastes (mainly nitrogenous wastes) from the body is known as 'excretion' (ex: out, crete: flow).
or
Excretion is the process of removal of harmful and unwanted nitrogenous waste products from the body.
Definition: Excretory System
Organs which are concerned with the formation, storage and elimination of urine constitute the 'excretory system'.
Define the following term:
Kidney
Kidneys are the primary excretory organs, eliminating nitrogenous wastes (chiefly urea) from the blood and throwing it out in the form of urine.
Define the following:
Excretory organs
During different metabolic activities taking place in our body, the body produces many substances of which some are useful and some are useless.
If retained in the body the unwanted substances may become poisonous and cause much harm and in severe cases, even death. The organs which remove these unwanted and toxic substances from the body are called excretory organs.
Define the following:
Excretion
During different metabolic activities taking place in our body, the body produces many substances, of which some are useful and some are useless.
The process of removing useless and harmful metabolic waste substances is called excretion.
The process of removal of chemical wastes (Mainly Nitrogenous) from the body is known as ''excretion''. It plays an important role in maintaining the homeostatic (steady-state) condition of the body.
Definition: Artificial Kidney
An artificial kidney is a dialysis machine that removes urea and excess salts from the blood when both kidneys fail, and returns the purified blood back into the body.
Definition: Dialysis
Dialysis is a medical process in which nitrogenous wastes and toxic substances are removed from the blood using an artificial machine when the kidneys fail to function properly.
Define stimulus.
A stimulus is an agent or a sudden change in the external or internal environment that changes an organism or body parts. e.g., light, sound, heat, pain, hunger.
Define the following:
Motor neuron:
The neurons which carry impulses from the brain or spinal cord to the body parts are called motor or efferent neurons.
Define the following:
Neuron
Neurons are the building blocks of the nervous system and transmit information throughout the body.
Define the term:
Sensory neuron
The neurons which carry impulses from the body parts to the spinal cord or the brain are called sensory or afferent neurons. For example, the optic nerve of the eye.
Define the following:
Reflex arc
The path that an impulse takes in a reflex action is called a reflex arc.
Key Points
Key Points: Transportation of Water
- Xylem vessels and tracheids form a continuous network that carries water and minerals from roots to all parts of the plant.
- Water enters the roots due to active absorption of ions, creating a concentration difference that pulls water in from the soil.
- Transpiration is the loss of water vapour from the aerial parts of the plant, mainly through stomata, and creates a suction pull that draws water upward.
- Transpiration pull is the main force for upward water movement during the day, while root pressure plays a bigger role at night.
Key Points: Excretion in Plants
Key Points: Human Nervous System
- Receptors in sense organs detect changes in the environment and send signals to the brain through neurons.
- A neuron consists of dendrites, cell body, and axon, which help in receiving and transmitting electrical impulses.
- The electrical impulse travels from the dendrite to the axon terminal and then is passed to the next neuron or target cell.
- At the synapse, special chemicals help transmit the impulse to another neuron or to a muscle or gland.
- A neuromuscular junction allows the nerve impulse to reach a muscle fibre, causing it to contract and respond.
Key Points: Different regions of Brain and its functions:
| Part | Description | Location | Structure | Main Functions |
|---|---|---|---|---|
| Cerebrum | Largest part of the brain, also called the large brain | Upper part of cranial cavity | Two hemispheres with many convolutions | Voluntary actions; intelligence, memory, thinking, decision-making |
| Cerebellum | Smaller part of brain situated below cerebrum | Back of cranial cavity | Shallow grooves on surface | Coordination of movements; body balance |
| Medulla Oblongata | Hindmost part of brain connecting brain to spinal cord | Lower brainstem | Pyramidal structures; continuous with spinal cord | Controls breathing, heartbeat, swallowing, coughing |
| Spinal Cord | Long cylindrical part of CNS extending from medulla | Vertebral column | Ends as filum terminale | Reflex actions; conduction of impulses to and from brain |
Concepts [16]
- Transportation in Living Organisms
- Transportation in Plants
- Transportation of Water
- Transportation of Food and Other Substances
- Excretion
- Excretion in Plants
- Human Excretory System
- Dialysis and Artificial Kidney
- Need for Control and Coordination in Organisms
- Control and Co-ordination in Plants
- Control and Co-ordination in Human Being
- Nervous Control
- Human Nervous System
- Central Nervous System (CNS)
- Chemical Control
- Endocrine Glands: Location and Important Functions
