BIOL 101 Homework Learn It Lifeforms solutions complete answers

BIOL 101 Homework Learn It Lifeforms solutions complete answers 

 

Learn It: Describe the common features of all lifeforms.
What does it mean to be alive? What key features or characteristics are common to all living things?

Let's start with one of the most basic and obvious key features of all living things. How does any living thing get here in the first place? All organisms are offspring of their predecessors and are generated by the process of reproduction. Although reproduction can vary dramatically from one organism to the next, when an organism produces offspring, the offspring receives hereditary information in the form of DNA. All organisms receive their DNA from their predecessors or parents, whether an organism is as simple as a bacterium receiving DNA from one parent or something much more complex like you, receiving DNA from two parents. This process of transmitting DNA from parent to offspring is called inheritance, and it is not only intimately related to the process of reproduction, but also essential to the continuance of all life forms.

As you know, even complex organisms begin as a single cell. For instance, you began as a single fertilized egg. As you developed from a single cell into a much larger multicellular organism, you increased in size, volume, and number of cells. Growth was a natural prerequisite. Can you imagine the amount of energy required to fuel that kind of growth? All organisms require energy to fuel these processes, and that energy comes in the form of nutrients. All living things require nutrients, but how they acquire nutrients may vary.

Consider the many types of plants growing in the world around you. All of them can harness the energy of sunlight to produce sugar from atmospheric CO2 and water in a process called photosynthesis. This is why they are categorized as producers; they can produce their own food. However, not all organisms are capable of photosynthesis. In this case, nutrients and the energy stored in them can be acquired by consuming other organisms. Whether it's a caterpillar eating a leaf, a rabbit nibbling on carrots, or you enjoying a garden salad for dinner, the nutrients and therefore energy previously stored within one organism is being transferred to another. This type of energy transfer occurs when one organism consumes another. This is why organisms that obtain their energy from other organisms are categorized as consumers. As energy flows from one organism to another, that energy is used by organisms to fuel growth, development, and reproduction. The transfer of energy, such as from a carrot to a rabbit, is not, however, completely efficient. While some of that energy will be used by the rabbit for growth, development, and reproduction, some of that energy will also be lost to the environment in the form of heat. 

 

Aside from acquiring energy for growth, development, and reproduction, organisms must also be able to sense and respond to changes occurring both within them and within their environment. For example, the rabbit in the figure has big ears that have a large surface area and contain lots of blood vessels. If the rabbit's body temperature gets too high on a hot day, the rabbit's body can increase blood flow to the rabbit's ears and, in turn, increase the amount of heat lost through radiation! The process of keeping internal conditions, such as body temperature, within an optimal range is called homeostasis. The ability to maintain homeostasis is yet another key feature of all living organisms that increases the likelihood of survival.

 

Which key feature of living organisms is best described as the transmission of DNA from parent to offspring?

     Homeostasis

   Response to changes

   Growth

   Inheritance

 

What is the main source of energy for producers?

     Plants

   Organisms

   Sunlight

   Consumers

 

When energy is transferred from one organism to another, some energy is lost to the environment due primarily to _____.

     the transmission of DNA

   the release of heat

   reproduction

   growth

 

 involves an increase in volume, cell number, or cell size, and is powered by energy derived from 

Growth, nutrients

 

Energy from the sun is directly harnessed by , which can be  by other organisms.

producers, consumed