1 - Nature and Variety of living organisms Flashcards
What is the criteria to determine a living organism
Movement
Respiration
Sensitivity
Control
Growth
Reproduction
Excretion
Nutrition
If something doesn’t carry out all of these processes it is dead or non living.
What is Nutrition
Organisms must obtain food to provide energy, it is necessary to carry out life processes.
What nutrition occours in plants
Plants use sunlight, carbon dioxide and water to produce oxygen and glucose in the process of photosynthesis
Because plants create their own food for energy, they are described as being autotrophic
What nutrition occours in animals
Animals consume other living organisms in order to obtain the energy they require
They break down larger complex molecules into simpler molecules through the process of digestion
As animals obtain their food from a range of different sources, they are described as being heterotrophic
What is Respriation
Respiration is a chemical reaction carried out in all living organisms
Energy is released from glucose either in the presence of oxygen (aerobic respiration) or the absence of oxygen (anaerobic respiration)
The reactions ultimately result in the production of carbon dioxide and water as waste products
Energy is transferred in the form of ATP
What is Excretion
Chemical reactions that take place inside living cells are described as metabolic reactions
Metabolic reactions produce waste products, some of which may be toxic
These toxic products must be eliminated from the body
Excretion is the removal of toxic materials and substances from organisms
What excretion occours in animals
Carbon dioxide from respiration
Water from respiration and other chemical reactions
Urea which contains nitrogen resulting from the breakdown of proteins
What excretion occours in plants
Oxygen from photosynthesis
Carbon dioxide from respiration
Water from respiration and other chemical reactions
What is Response to Surrondings
The sensitivity of an organism refers to its ability to detect and respond to stimuli in its surroundings
Responding to the environment around them gives an organism the best chances of survival
What is the Response to surrondings in humans
Sensitivity responses in animals
In humans, the nervous system provides a complex system of receptors, neurones and effectors which detect and respond to different stimuli using electrical impulses
The endocrine system also allows a response to stimuli using chemical messengers, which travel in the blood, called hormones
What Sensitivity responses occour in plants
In plants, responses are controlled by chemicals and are usually much slower
Geotropism describes a plants response to gravity which causes the roots to grow down into the soil
Phototropism describes a plant’s response to light which causes shoots to grow towards sunlight
What is Movement
Movement is an action by an organism causing a change of position or place
The movement of an organism from place to place is called locomotion
Plants cannot move from place to place but can change their orientation
What is control
Living organisms must control their internal environment in order to keep conditions within required limits
This is called homeostasis
What control happenes in humans
Thermoregulation refers to the control of body temperature
The optimum human body temperature is 37°C
If body temperature increases e.g. during exercise, mechanisms for control will be initiated to return the temperature back to the optimum
Mechanisms include sweating or vasodilation
Other homeostatic mechanisms in humans include glucoregulation (control of blood glucose levels) and osmoregulation (control of water levels)
What is control in plants
Plants use transpiration to maintain a suitable temperature
Water evaporates from the stomata on the underside of the leaf, leading to heat loss