None of the physical properties listed below can be determined through measurement. A material's freezing point can be determined by keeping track of the temperature the material is exposed to colder and colder temperatures until it freezes. The temperature this happens is decided after multiple trials determine its freezing point. A material's boiling point is discovered by measuring a rising temperature until the material comes to a rolling boil. Both of these physical properties are measured with a thermometer. Finally, whether a material conducts electricity depends on what the sample is made up of. Things like wood, plastic, and cloth do not conduct electricity well, while metal and copper do. The electrical conductivity can be calculated by measuring the resistance, area, and length of the test material. You can also use a four-terminal ohmmeter for greater accuracy. All of these physical properties require testing and the use of measurement to determine.

The statement "Color is a physical property that is determined through observation." is true. Color cannot be measured with a tool but is a physical property that is gathered using one of the five senses. Our sense of sight allows us to see color and make determinations about what we are observing. We would not use a ruler or thermometer to determine a material's color.

Photosynthesis is the way in which plants convert the sun's energy into their own energy. And since animals get their energy from food, when an animal eats a plant it gets its plant-based energy indirectly from the sun, because that's how the plant itself got energy. Then when a carnivore eats a plant-eating animal, the carnivore gets energy from the herbivore, who got its energy from the plant, which got it from the sun. So even meat-eaters indirectly get their energy from the sun.

The food chain is highly interdependent in any given habitat, so if the plant-eating impalas and deer that leopards eat were suddenly to lose their plant-based food sources, they would die out and the leopards wouldn't have much left to eat. All nutritional energy comes from the sun: plants use chlorophyll to photosynthesize the sun's energy into plant energy, and then animals either feed on plants for that energy or they feed on the animals that have eaten that plant energy. A loss in plants means that the solar energy that supplies even the most ferocious carnivores will be less plentiful.

The food chain begins with the sun: plants get their energy by photosynthesizing sunlight into energy, and then herbivores eat those plants to get their energy. Carnivores who then eat the herbivores are getting that sunlight passed along from sun to plant to herbivore to carnivore. So if the sun were to no longer shine in this habitat, plants would not convert sunlight to energy, so mice would die, meaning that the hawks would have nothing to eat, and the vultures wouldn't get to feast on the scraps.  

Through the photosynthesis process, producers, such as grass, absorb the sun's light energy to produce food (stored sugar and starches). Consumers cannot make their own food, so they have to consume other organisms. The food of almost any kind of animal can be traced back to plants and the sun. Organisms are related in food webs in which some animals eat plants for food and other animals eat the animals that eat plants. Some organisms, such as fungi and bacteria, break down dead organisms (both plants or plant parts and animals) and therefore operate as “decomposers.” Decomposition eventually restores (recycles) some materials back to the soil. Organisms can survive only in environments in which their particular needs are met.

Through the photosynthesis process, producers, such as grass, absorb the sun's light energy to produce food (stored sugar and starches). Consumers cannot make their own food, so they have to consume other organisms. The food of almost any kind of animal can be traced back to plants and the sun. Organisms are related in food webs in which some animals eat plants for food and other animals eat the animals that eat plants. Some organisms, such as fungi and bacteria, break down dead organisms (both plants or plant parts and animals) and therefore operate as “decomposers.” Decomposition eventually restores (recycles) some materials back to the soil. Organisms can survive only in environments in which their particular needs are met.

All nutritional energy comes from the Sun: plants use chlorophyll to photosynthesize the Sun's energy into plant energy, and then animals either feed on plants for that energy or they feed on the animals that have eaten that plant energy. The food chain begins with the Sun and then the energy flows to producers.

All nutritional energy comes from the Sun: plants use chlorophyll to photosynthesize the Sun's energy into plant energy. Then animals either feed on plants for that energy, or they feed on the animals that have eaten that plant energy. An arrow would be facing outwards, displaying energy leaving the Sun and being consumed by a producer, but no arrow facing towards it because the Sun does not consume energy in the food chain.

Producers rely on the Sun to make the food needed to survive. Through photosynthesis, plants convert sunlight and carbon dioxide into oxygen, sugar, and carbohydrates. Without the Sun, plants would be missing an essential "ingredient" to create their nutrients and would not survive.