1 Characteristics of Living Organisms

Question 1

What does the acronym MRS C GREN stand for?

Answer 1

Movement
Respiration
Sensitivity
Control
Growth
Reproduction
Excretion
Nutrition
If something does not carry out all of these life processes, it is either dead or non-living.

Question 2

What is nutrition in plants?

Answer 2

Plants use sunlight, carbon dioxide and water to produce oxygen and glucose in the process of photosynthesis.

Question 3

Because plants create their own food for energy, they are described as being….?

Answer 3

Autotrophic

Question 4

How do animals break down larger complex molecules into simpler molecules?

Answer 4

Through the process of digestion.

Question 5

As animals obtain their food from a range of different sources, they are described as being….?

Answer 5

Heterotrophic

Question 6

What is the word equation for aerobic respiration?

Answer 6

Glucose + oxygen —–> carbon dioxide + water

Question 7

Chemical reactions that take place inside living cells are described as….?

Answer 7

Metabolic reactions
(Metabolic reactions produce waste products, some of which may be toxic
These toxic products must be eliminated from the body)

Question 8

What is excretion?

Answer 8

Excretion is the removal of toxic materials and substances from organisms.

Question 9

Waste products excreted by animals include:

Answer 9

Carbon dioxide from respiration, water from respiration and other chemical reaction, urea which contains nitrogen resulting from the breakdown of proteins.

Question 10

Waste products excreted by plants include:

Answer 10

Oxygen from photosynthesis, carbon dioxide from respiration, water from respiration and other chemical reactions.

Question 11

What does the sensitivity of organisms refer to?

Answer 11

Its ability to detect and respond to stimuli in its surroundings. (Responding to the environment around them gives an organism the best chances of survival.)

Question 12

In humans, the nervous system provides a complex system of ….?

Answer 12

Receptors, neurones and effectors which detect and respond to different stimuli using electrical impulses.

Question 13

What is the endocrine system?

Answer 13

It allows a response to stimuli using chemical messengers, which travel in the blood, called hormones.

Question 14

Sensitivity responses in plants

Answer 14

In plants, responses are controlled by chemicals and are usually much slower

Question 15

What is geotropism?

Answer 15

Describes a plants response to gravity which causes the roots to grow down into the soil

Question 16

What is Phototropism

Answer 16

Describes a plant’s response to light which causes shoots to grow towards sunlight.

Question 17

What is homeostasis?

Answer 17

Living organisms must control their internal environement in order to keep conditions within required limits.

Question 18

Homeostasis in Humans

Answer 18

• Thermoregulation refers to the control of body temperature.
• The optimum human body temperature is 37 degrees celcius. If body temperature increases e.g. during exercise, mechanisms for control will be initiated to return the temperature back to optimum. Mechanisms include sweating, vasodilation and osmoregulation.

Question 19

Homeostasis in Plants

Answer 19

• Plants use transpiration to maintain a suitable temperature.
• Water evaporates from the stomata on the underside of the leaf, leading to heat loss.

Question 20

Sexual Reproduction

Answer 20

The male and female gametes fuse together. In humans, the male gamete is the sperm and the female gamete is the egg. In plants, the male gamete is the pollen grains and the female gamete is the ovule.

Question 21

Asexual Reproduction

Answer 21

Mitosis is an example of asexual reproduction. There is only one parent involved so an exact clone is produced. The DNA of the offspring is identical to parental DNA. Plants can reproduce asexually through tubers, budding or runners. Single-celled organisms such as bacteria or amoeba reproduce asexually.

Question 22

What are the five kingdoms of living organisms.

Answer 22

Animals, plants, fungi, protoctists and prokaryotes.

Question 23

Eukaryotic organisms

Answer 23

Animals, plants, fungi and protoctists are all eukaryotic organisms. Eukaryotic organisms can be multicellular or single-celled and are made up of cells that contain a nucleus with a distinct membrane.

Question 24

Prokaryotic organisms

Answer 24

Prokaryotic organisms (also known as prokaryotes) are in a separate kingdom and are different from eukaryotes as they are always single-celled and do not contain a nucleus (instead, the nuclear material of prokaryotic cells is found in the cytoplasm)
Bacteria are prokaryotic organisms
Prokaryotic cells are substantially smaller than eukaryotic cells.

Question 25

What are the main features of animals?

Answer 25

They are multicellular
Their cells contain a nucleus with a distinct membrane
Their cells do not have cellulose cell walls
Their cells do not contain chloroplasts (so they are unable to carry out photosynthesis)
They feed on organic substances made by other living things
They often store carbohydrates as glycogen
They usually have nervous coordination
They are able to move from place to place

Question 26

What are the main features of plants?

Answer 26

They are multicellular
Their cells contain a nucleus with a distinct membrane
Their cells have cell walls made out of cellulose
Their cells contain chloroplasts (so they can carry out photosynthesis)
They feed by photosynthesis
They store carbohydrates as starch or sucrose
They do not have nervous coordination.

Question 27

Cell structures found in both animal and plants

Answer 27

Nucleus, cytoplasm, cell membrane, ribosomes and mitochondria

Question 28

What is the function of the nucleus?

Answer 28

• Contains the genetic material (DNA) which controls the activities of the cell.

Question 29

What is the function of the cytoplasm?

Answer 29

• A gel-like substance composed of water and dissolved solutes.
• Supports internal cell structures
• Site of many chemical reactions, including anaerobic respiration.

Question 30

What is the function of the cell membrane?

Answer 30

• Holds the cell together, separating the inside of the cell from the outside
• Controls which substances can enter and leave the cell.

Question 31

What is the function of the ribosomes?

Answer 31

• Found in the cytoplasm
• Site of protein synthesis

Question 32

What is the function of the mitochondria?

Answer 32

• Site of most of the reactions involved in aerobic respiration, where energy is released to fuel cellular processes.
• Cells with high rates of metabolism (carrying out many different cell reactions) have significantly higher numbers of mitochondria than cells with fewer reactions taking place.

Question 33

Cell structures found only in plant cells

Answer 33

Cell wall, chloroplasts and permanent vacuole

Question 34

What is the function of the cell wall?

Answer 34

• Made of cellulose (a polymer of glucose)
• Gives the cell extra support, defining its shape.

Question 35

What is the function of the chloroplasts?

Answer 35

• Contains green chlorophyll pigments (to absorb light energy) and the enzymes needed for photosynthesis.

Question 36

What is the function of a permanent vacuole?

Answer 36

• Contains cell sap; a solution of sugars and salts dissolved in water
• Used for storage of certain materials
• Also helps support the shape of the cell.

Question 37

What are the main features of fungi?

Answer 37

They are usually multicellular but some are single-celled (e.g. yeast)
Multicellular fungi are mainly made up of thread-like structures known as hyphae that contain many nuclei and are organised into a network known as a mycelium
Their cells contain a nucleus with a distinct membrane
Their cells have cell walls made of chitin (chitinous cell walls)
Their cells do not contain chloroplasts (so they cannot carry out photosynthesis)
They feed by secreting extracellular digestive enzymes (outside the mycelium) onto the food (usually decaying organic matter) and then absorbing the digested molecules. This method of feeding is known as saprotrophic nutrition
Some fungi are parasitic and feed on living material
Some fungi store carbohydrates as glycogen
They do not have nervous coordination
Examples of fungi include: moulds, mushrooms, yeasts

Question 38

What are the main features of protoctists?

Answer 38

• They are mainly microscopic and single-celled but some aggregate into larger forms, such as colonies or chains of cells that form filaments.
• Their cells contain a nucleus with distinct membrane.
• Some have features making them more like animal cells
• Some have features, such as cell walls and chloroplasts, making them more like plant cells
• This means some protoctists photosynthesise and some feed on organic substances made by other living things.
• They do not have nervous coordination.
• Examples of protoctists include: amoeba and Chlorella

Question 39

What are the main features of bacteria?

Answer 39

• They are microscopic single-celled organisms
• They have a cell wall (not made of cellulose), cell membrane, cytoplasm and plasmids
• They lack a nucleus but contain a circular chromosome of DNA
• They lack mitochondria and other membrane-bound organelles found in eukaryotic cells

Question 40

How do bacteria feed?

Answer 40

• Some bacteria can carry out photosynthesis despite having no chloroplasts. This is because they still possess chlorophyl and enzymes necessary to synthesize sugars from carbon dioxide.
• Most feed on other living or dead organisms (if they feed on dead organic matter then they are known as saprobionts or decomposers)

Question 41

What microorganisms are examples of pathogens?

Answer 41

Bacteria, fungi, protoctists and viruses.

Question 42

Viruses biological characteristics

Answer 42

• They are small particles (always smaller than bacteria).
• They are parasitic and can only reproduce inside living cells.
  -They infect every type of living organism.
• They have no cellular structure but have a protein coat and contain one type of nucleic acid, either DNA or RNA.