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Watch this video to see how plants respond to a stimulus—from opening to light, to wrapping a tendril around a branch, to capturing prey.

Reproduction

Single-celled organisms reproduce by first duplicating their DNA, and then dividing it equally as the cell prepares to divide to form two new cells. Multicellular organisms often produce specialized reproductive germline cells that will form new individuals. When reproduction occurs, genes containing DNA are passed along to an organism’s offspring. These genes ensure that the offspring will belong to the same species and will have similar characteristics, such as size and shape.

Growth and development

Organisms grow and develop following specific instructions coded for by their genes. These genes provide instructions that will direct cellular growth and development, ensuring that a species’ young ( [link] ) will grow up to exhibit many of the same characteristics as its parents.

A photograph depicts a mother cat nursing three kittens: one has an orange and white tabby coat, another is black with a white foot, while the third has a black and white tabby coat.
Although no two look alike, these kittens have inherited genes from both parents and share many of the same characteristics. (credit: Rocky Mountain Feline Rescue)

Regulation

Even the smallest organisms are complex and require multiple regulatory mechanisms to coordinate internal functions, respond to stimuli, and cope with environmental stresses. Two examples of internal functions regulated in an organism are nutrient transport and blood flow. Organs (groups of tissues working together) perform specific functions, such as carrying oxygen throughout the body, removing wastes, delivering nutrients to every cell, and cooling the body.

Homeostasis

A photos shows a white, furry polar bear.
Polar bears ( Ursus maritimus ) and other mammals living in ice-covered regions maintain their body temperature by generating heat and reducing heat loss through thick fur and a dense layer of fat under their skin. (credit: “longhorndave”/Flickr)

In order to function properly, cells need to have appropriate conditions such as proper temperature, pH, and appropriate concentration of diverse chemicals. These conditions may, however, change from one moment to the next. Organisms are able to maintain internal conditions within a narrow range almost constantly, despite environmental changes, through homeostasis    (literally, “steady state”)—the ability of an organism to maintain constant internal conditions. For example, an organism needs to regulate body temperature through a process known as thermoregulation. Organisms that live in cold climates, such as the polar bear ( [link] ), have body structures that help them withstand low temperatures and conserve body heat. Structures that aid in this type of insulation include fur, feathers, blubber, and fat. In hot climates, organisms have methods (such as perspiration in humans or panting in dogs) that help them to shed excess body heat.

Energy processing

Photo shows a California condor in flight with a tag on its wing.
The California condor ( Gymnogyps californianus ) uses chemical energy derived from food to power flight. California condors are an endangered species; this bird has a wing tag that helps biologists identify the individual. (credit: Pacific Southwest Region U.S. Fish and Wildlife Service)

Questions & Answers

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Ndolase Reply
what are products of the light reactions of photosynthesis that are utilised in the Calvin cycle?
Nellie Reply
light stage reaction of photosynthesis is represented in the chemical equation ; 4H+ >>>>>> ²H20 + O2 (Hydroxyl). (water) (oxygen)
Emmanuel
a man with blood group A married a woman with blood group B,their child has blood group O,what are the genotype of the parents
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your question is not clear
Emmanuel
Ai woman Bi man
INGIPHILE
Is this a science student asking question
Sando
how are living organisms grouped?
Jimmy Reply
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Isaiah Reply
what are the vital components of biochemistry
Isaiah
what is the importance of cells
Samuel Reply
epiphytes grow on branches of large trees and competing for light in the canopy by climbing up those large trees while using them for support at same time. what type of ecological interaction is seen here?
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eunice
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Jimmy
what will the under secretion of somatotropin result
Jovita Reply
The under secretion of Somatotropin growth hormone results in DWARFISM, a condition of retarded growth....
Emmanuel
what are nutrients needed by plants
Mabeni Reply
calcium, phosphorus, potassium, nitrogen ,magnesium
Shukurat
why is the cell made up of celullose wall
Mungudit Reply
what are prokaryotic and eukàryotic
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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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