Unicellular and Multicellular Flashcards
Define Unicellular
an organism made up of a single cell
Give some examples of unicellular organisms
Paramecium, most prokaryotes
Define multicellular
Describes an organism consisting of more than one cell
Give some examples of multicellular organisms
Animals, humans, insects, plants etc…
What are protozoans?
group of heterotrophic unicellular eukaryotes belonging in the kingdom of Protista
What are heterotrophs?
an organism that cannot synthesis its own organic compounds from single inorganic material and so rely on autotrophs (organic substances) to provide energy for them, usually by being consumed.
Eg. All animals, protozoan, fungi and most bacteria are heterotrophs, animals
What is a colony of cells?
an organised association of unicellular organisms.
eg. volvox
What are the 3 organising principles required for the evolution from unicellular organisms to multicellular?
The ability of cells to divide, specialise and communicate with other cells.
MRS GREN
Movement
Reproduction
Sensitivity
Growth
Respiration
Excretion
Nutrition
How does cell specialisation and differentiation occur?
the diversity of cell shape and structure reflects the evolutionary adaptions of cells to different environments
What is cellular differentiation?
the process by which an unspecialised cell develops into a specialised cell
What are 3 differences stem cells have that make them different from other cells in the body?
1st difference: they are unspecialised (have not yet specialised into a particular type of cell)
2nd difference: is that they have the potential to divide and replicate for long periods of time
3rd difference: relatively unspecialised cells can differentiate to form different specialised cells
What are stem cells?
cells that specialised cells originate from
What are the disadvantages of specialised cells?
The need for communication and co-ordination between cells, specialised cells are totally dependent on activities of other cells to perform tasks they can’t do.
What are specialised cells important?
They increase efficiency and reduce duplication of effort
What are the 4 basic types of tissue?
Connective tissue
Epithelial tissue
Nervous tissue
Muscle tissue
What are connective tissue?
It provides support and holds various part of the body together.
Give 4 examples of connective tissue.
Vertebrates
Cartilage
Bone
Blood
What are epithelial tissue?
Covering that protects organs, lines body cavities and covers the surface of the body.
How are epithelial tissues organised and how does it help them?
Organised into tightly packed single or layered sheets.
This increase their effectiveness as barriers that protects against mechanical injury, invasive micro organisms and loss of fluid.
Give examples of what epithelial tissues line.
Lines internal and external surface such as blood vessels, digestive organs, kidney tubules, skin and airways.
What are nervous tissue?
Means of communication between all body structures, and the cells in nervous tissue are highly specialised
Give examples of nervous tissues.
Nerves, motor neuron, sensory neuron
What are muscle tissue?
made of thin and very long thread-like cells called muscle fibres
Functions: posture and body support, locomotion and heat production
What are the two systems that organs of plants are grouped in?
Shoot system
Root system
What is the shoot system?
Comprised of all parts of the plant found above ground. Responsible for supporting the plant physically and the transportation of resources, as well as the absorption of oxygen and carbon dioxide, reproduction and carrying out photosynthesis in leaves
What is the root system?
Below ground
Responsible for absorbing water and nutrients from the soil
What are the 4 main types of plant tissues?
Meristematic tissue
Dermal tissue
Ground tissue
Vascular tissue
What is meristematic tissue?
Composed of cells that undergo cell division by mitosis, the process by which plants grow.
Meristems are the only places in a plant where cell divide.
Found at the tips of roots and shoots, in a ring around the inside of stems and bracts
What is dermal tissue?
Composed of the outermost cell layers of a plant
Epidermis
Protects plant from cuts, invasion by microorganisms and water loss
What is ground tissue?
Composed of all the internal cells of a plant other than vascular tissue.
Consists of a variety of different cell types that are specialised for storage, support and photosynthesis
Eg. Fleshy portions of apples, pears,etc…
What are the key roles of connective tissue?
Its key role is binding and supporting other tissues, and protects against damage, infection and heat loss
What are the functions of epithelial tissue?
Functions of epithelial cells include secretion, selective absorption, protection, transcellular transport, and sensing.
