Nutrition

PARASITIC NUTRITION

parasite - an organism that for part or all of its life derives its food from a living organism of another species (the host).
Some parasites (e.g. tapeworms) live in nutrient-rich media and no longer have a digestive system as their food is predigested by the host and the host’s enzymes. They absorb their nutrients directly across their body surface. (Humans can become infected by eating meat containing the tapeworm larvae.)

SAPROPHYTIC NUTRITION

Also known as saprobic or saprotrophic nutrition
Saprotroph - a bacterium, fungus or plant that feeds on dead or decaying organic matter. Most fungi and bacteria are saprobes - involved in the decay of organic matter.
Important for returning complex organic matter to CO₂ and H₂O and recycling of nutrients._ _ _ _ _ _ _ _ _ _ _ _ _Without these activities, essential nutrients would remain locked up in dead animal bodies, faeces, branches, logs etc and be unavailable for further use by new generations of organisms.
Generally these organisms live in/on their food, secrete enzymes to break down the food and absorb the simpler products of the digestion.
An important aspect of this is the specialisation for degradation of cellulose and lignin, the major part of terrestrial plant’s dry weight, unlike bacteria many fungi do this.

Feeders

FEEDING ADAPTATIONS

Terrestrial plants have tough cell walls (why?) so breaking the cell walls and digesting cellulose are problems to be overcome.
Some animals have symbiotic micro-organisms in their g-i tract that produce cellulase and allow digestion of cellulose into substances their hosts can absorb. E.g. Termites & herbivorous mammals (compare these with locusts and grasshoppers).
Compare terrestrial herbivorous, carnivorous and omnivorous mammals in the following categories: (1) dentition and (2) length and structure of the intestines.Aquatic plants are supported by surrounding water, they have little tough supporting tissues and are easily digested.Thus aquatic herbivores need no special adaptations except that some aquatic plants are tiny and are strained from the water so some of the herbivores aremicrophagous (filter) feeders, e.g. baleen whale, sponges, molluscs, some crustaceans, some birds (e.g. flamingo)
Filter feeding is non-selective, everything which is filtered is ingested, what can be used is digested & the remainder is egested.Macrophagous feedersIncludes animals that have mechanisms for
(a) Ingestion of inactive masses e.g. earthworms and detritus feeders
(b) Scraping, boring, biting, chewing e.g. sea-urchins, snails, insects and vertebrates
(c) Capture and swallowing of prey e.g. fish, snakes, birds, bats
There is an extensive range of modifications for acquiring food (radula, teeth, beaks, fangs)
Fluid feedersHave modifications for piercing or sucking, e.g. some worms (leeches), insects (mosquito), birds (_ _ _ _ _ _ _ _ _ _ _) and mammals (_ _ _ _ _ _ _ _ _ _).

Physics of projectile motion

What is a Projectile?

In Unit 1 of the Physics Classroom Tutorial, we learned a variety of means to describe the 1-dimensional motion of objects. In Unit 2 of the Physics Classroom Tutorial, we learned how Newton's laws help to explain the motion (and specifically, the changes in the state of motion) of objects that are either at rest or moving in 1-dimension. Now in this unit we will apply both kinematic principles and Newton's laws of motion to understand and explain the motion of objects moving in two dimensions. The most common example of an object that is moving in two dimensions is a projectile. Thus, Lesson 2 of this unit is devoted to understanding the motion of projectiles.

A projectile is an object upon which the only force acting is gravity. There are a variety of examples of projectiles. An object dropped from rest is a projectile (provided that the influence of air resistance is negligible). An object that is thrown vertically upward is also a projectile (provided that the influence of air resistance is negligible). And an object which is thrown upward at an angle to the horizontal is also a projectile (provided that the influence of air resistance is negligible). A projectile is any object that once projected or dropped continues in motion by its own inertia and is influenced only by the downward force of gravity.

By definition, a projectile has a single force that acts upon it - the force of gravity. If there were any other force acting upon an object, then that object would not be a projectile. Thus, the free-body diagram of a projectile would show a single force acting downwards and labeled force of gravity (or simply F_grav). Regardless of whether a projectile is moving downwards, upwards, upwards and rightwards, or downwards and leftwards, the free-body diagram of the projectile is still as depicted in the diagram at the right. By definition, a projectile is any object upon which the only force is gravity.