The Nature of Life Section 2-3: The Needs of Living Things

In order for a living organism to survive, it needs energy, food, water, oxygen, living space, and the ability to maintain a fairly constant body temperature.(p.55) This is a generalization – a broad statement that is not necessarily completely true for each specific case.

Need 1: Energy The primary source of energy for almost all living things is the sun The primary source of energy for almost all living things is the sun Many algae and almost all plants use the sun’s energy directly Many algae and almost all plants use the sun’s energy directly With a very few exceptions all other living things either eat plants or other animals that eat plants. (Remember food chains and webs.) With a very few exceptions all other living things either eat plants or other animals that eat plants. (Remember food chains and webs.) Photo by Hana KiranaHana Kirana

Need 2: Food The source of energy, whether the food is consumed or made The source of energy, whether the food is consumed or made The source of materials needed for growth, development and repair of the body The source of materials needed for growth, development and repair of the body Every organism has its own requirement for specific kinds of food, from fertilizer for plants to eucalyptus leaves for a koala to jellyfish for a sea turtle Photo by Arnaud Gaillard

Need 3: Water Makes up 65+% of your body’s mass Makes up 65+% of your body’s mass Many chemical reactions in cells require water to occur Many chemical reactions in cells require water to occur Necessary for transport of chemical substances throughout the bodies of higher life forms (plant’s sap and animal’s blood) Necessary for transport of chemical substances throughout the bodies of higher life forms (plant’s sap and animal’s blood)

Need 4: Oxygen Oxygen (O 2 ): Oxygen (O 2 ): Primarily necessary for the process of respiration (to provide energy) Primarily necessary for the process of respiration (to provide energy) A by-product of photosynthesis A by-product of photosynthesis RespirationPhotosynthesis

Need 4: Oxygen Oxygen (O 2 ): Oxygen (O 2 ): Primarily necessary for the process of respiration (to provide energy) Primarily necessary for the process of respiration (to provide energy) A by-product of photosynthesis A by-product of photosynthesis RespirationPhotosynthesis Uses Oxygen (O 2 )

Need 4: Oxygen Oxygen (O 2 ): Oxygen (O 2 ): Primarily necessary for the process of respiration (to provide energy) Primarily necessary for the process of respiration (to provide energy) A by-product of photosynthesis A by-product of photosynthesis RespirationPhotosynthesis Uses Oxygen (O 2 ) Uses Carbon dioxide (CO 2 )

Need 4: Oxygen Oxygen (O 2 ): Oxygen (O 2 ): Primarily necessary for the process of respiration (to provide energy) Primarily necessary for the process of respiration (to provide energy) A by-product of photosynthesis A by-product of photosynthesis RespirationPhotosynthesis Uses Oxygen (O 2 ) Uses Carbon dioxide (CO 2 ) Produces Carbon dioxide (CO 2 )

Need 4: Oxygen Oxygen (O 2 ): Oxygen (O 2 ): Primarily necessary for the process of respiration (to provide energy) Primarily necessary for the process of respiration (to provide energy) A by-product of photosynthesis A by-product of photosynthesis RespirationPhotosynthesis Uses Oxygen (O 2 ) Uses Carbon dioxide (CO 2 ) Produces Carbon dioxide (CO 2 ) Produces Oxygen (O 2 )

Need 5: Living Space Each living thing requires a certain amount of space. Each living thing requires a certain amount of space. Competition: The struggle among living things to obtain the proper amount of food, water and energy. Competition: The struggle among living things to obtain the proper amount of food, water and energy. What do you think determines how much living space an organism needs? Sea anemones compete for space in tide pools Photo by Brocken InagloryBrocken Inaglory

Need 6: Proper Temperature Generally each organism is adapted to live within a certain range of environmental temperatures. Prolonged exposure to temperatures outside that range usually lead to death. Photo by Alan D. Wilson at naturespicsonline.comnaturespicsonline.com Photo credit: Luc Viatour /

Homeostasis The ability of an organism to keep conditions inside its body the same, even though conditions in its external environment change Internal conditions include such things as: Body temperature for warm-blooded animals Body temperature for warm-blooded animals pH pH salt levels salt levels blood glucose levels blood glucose levels

Warm-blooded vs. Cold-blooded Terms used to describe vertebrate animals. Warm-blooded: animals that maintain a constant body temperature as the environment’s temperature changes (Mammals and Birds) Cold-blooded: animals whose body temperature changes somewhat as its environment’s temperature changes (Reptiles, Amphibians and Fish)

Warm-blooded vs. Cold-blooded Advantage of being warm-blooded: Can move around in hot or cold weather, day or night Can move around in hot or cold weather, day or night Disadvantage to being warm-blooded: Requires a lot of energy to maintain a constant body temperature (ex. A lion must eat 10 times what a crocodile eats) Requires a lot of energy to maintain a constant body temperature (ex. A lion must eat 10 times what a crocodile eats) Photo from Photo credit: Public Domain

Warm-blooded vs. Cold-blooded Adaptations that help warm-blooded animals maintain their body temperature include: For keeping warm - hair/fur, feathers, and shivering For keeping warm - hair/fur, feathers, and shivering For cooling – panting and sweating For cooling – panting and sweating Photo credit: WileyWiley Photo credit: KorallKorall