1 - Characteristics of Living Organisms

Question 1

What is the criteria to determine a living organism

Answer 1

Movement
Respiration
Sensitivity
Control
Growth
Reproduction
Excretion
Nutrition

If something doesn’t carry out all of these processes it is dead or non living.

Question 2

What is Nutrition

Answer 2

Organisms must obtain food to provide energy, it is necessary to carry out life processes.

Question 3

What nutrition occours in plants

Answer 3

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

Because plants create their own food for energy, they are described as being autotrophic

Question 4

What nutrition occours in animals

Answer 4

Animals consume other living organisms in order to obtain the energy they require

They break down larger complex molecules into simpler molecules through the process of digestion

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

Question 5

What is Respriation

Answer 5

Respiration is a chemical reaction carried out in all living organisms
Energy is released from glucose either in the presence of oxygen (aerobic respiration) or the absence of oxygen (anaerobic respiration)
The reactions ultimately result in the production of carbon dioxide and water as waste products
Energy is transferred in the form of ATP

Question 6

What is Excretion

Answer 6

Chemical reactions that take place inside living cells are described as metabolic reactions
Metabolic reactions produce waste products, some of which may be toxic
These toxic products must be eliminated from the body
Excretion is the removal of toxic materials and substances from organisms

Question 7

What excretion occours in animals

Answer 7

Carbon dioxide from respiration
Water from respiration and other chemical reactions
Urea which contains nitrogen resulting from the breakdown of proteins

Question 8

What excretion occours in plants

Answer 8

Oxygen from photosynthesis
Carbon dioxide from respiration
Water from respiration and other chemical reactions

Question 9

What is Response to Surrondings

Answer 9

The sensitivity of an organism refers to 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 10

What is the Response to surrondings in humans

Answer 10

Sensitivity responses in animals
In humans, the nervous system provides a complex system of receptors, neurones and effectors which detect and respond to different stimuli using electrical impulses
The endocrine system also allows a response to stimuli using chemical messengers, which travel in the blood, called hormones

Question 11

What Sensitivity responses occour in plants

Answer 11

In plants, responses are controlled by chemicals and are usually much slower
Geotropism describes a plants response to gravity which causes the roots to grow down into the soil
Phototropism describes a plant’s response to light which causes shoots to grow towards sunlight

Question 12

What is Movement

Answer 12

Movement is an action by an organism causing a change of position or place
The movement of an organism from place to place is called locomotion
Plants cannot move from place to place but can change their orientation

Question 13

What is control

Answer 13

Living organisms must control their internal environment in order to keep conditions within required limits
This is called homeostasis

Question 14

What control happenes in humans

Answer 14

Thermoregulation refers to the control of body temperature
The optimum human body temperature is 37°C
If body temperature increases e.g. during exercise, mechanisms for control will be initiated to return the temperature back to the optimum
Mechanisms include sweating or vasodilation
Other homeostatic mechanisms in humans include glucoregulation (control of blood glucose levels) and osmoregulation (control of water levels)

Question 15

What is control in plants

Answer 15

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

Question 16

What is Reproduction

Answer 16

Reproduction is the process that leads to the production of more of the same kind of organism
Reproduction is fundamental to the survival of a population and ultimately, the species
There are different types of reproduction: sexual and asexual

Question 17

What Reproduction occours in Animals

Answer 17

In this type of reproduction, 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 in the pollen grains and the female gamete is the ovule
The DNA of the offspring is composed of both maternal and paternal DNA

Question 18

What type of reproduction happenes in Animals

Answer 18

Cells or whole organisms can also reproduce using asexual reproduction
Mitosis is an example of asexual reproduction
There is only one parent involved so an exact clone is produced
The DNA of 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 19

What is Growth

Answer 19

Growth is defined as a permanent increase in size
In animals, an individual grows larger between the zygote and adult stage with changes in proportion or shape
In plants, an individual grows larger throughout their whole life with new shoots, leaves, branches etc forming year after year

Question 20

What are the 5 living kingdoms

Answer 20

Animals
Plants
Fungi
Protoctists
Prokaryotes

Question 21

What are Eukaryotic organisms

Answer 21

Eukaryotic organisms can be multicellular or single-celled and are made up of cells that contain a nucleus with a distinct membrane

Question 22

What are Prokaryotic organisms

Answer 22

Prokaryotic organisms 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 23

What are the main features of Plants

Answer 23

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 24

What are structures only found in plant cells

Answer 24

Cell wall- Made of cellulose gives the cell extra support and defines it shape

Chloroplasts- Contains Green Chlorophyll Pigments absorb light energy and enzymes needed for photosynthesis

Permanent Vacuole- Contains cell sap; solution of sugars and salts dissolved in water. Used for storage of certain materials, also helps support the shape of the cell

Question 25

What are the main features of Fungi

Answer 25

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 26

What are the features of Bacteria

Answer 26

Bacteria, which have a wide variety of shapes and sizes, all share the following biological characteristics:
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
Examples of bacteria include:
Lactobacillus (a rod-shaped bacterium used in the production of yoghurt from milk)
Pneumococcus (a spherical bacterium that acts as the pathogen causing pneumonia)
Bacteria feed in different ways:
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 27

What are the main features o protoctists

Answer 27

The protoctists are a very diverse kingdom of organisms that don’t really belong in any of the other eukaryotic kingdoms (animals, plants and fungi)
They are mainly microscopic and single-celled but some aggregate (group together) into larger forms, such as colonies or chains of cells that form filaments
Their cells contain a nucleus with a distinct membrane
Some have features making them more like animal cells e.g. Plasmodium (the protoctist that causes malaria)
Some have features, such as cell walls and chloroplasts, making them more like plant cells e.g. green algae, such as Chlorella
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, Paramecium, Plasmodium, Chlorella

Question 28

What is a pathogen

Answer 28

A pathogen is any microorganism that causes disease in another organism (e.g. in plants or animals)

Question 29

Give examples of microorganism that are pathogens

Answer 29

Bacteria
Fungi
Protoctists
Viruses

Question 30

What are pathogenic bacteria

Answer 30

Pathogenic bacteria do not always infect the hosts of cells, they can remain within body cavities or spaces
M. tuberculosis causes tuberculosis (TB) in humans
The bacteria infect the lungs, causing a chronic cough and bloody mucus
It is a disease often associated with poor hygiene and sanitation
M. bovine in cows can also transmit to humans to cause TB

Question 31

What are pathogenic fungi

Answer 31

Fungal diseases are much more common in plants than animals
Cattle ringworm and athletes foot are fungal diseases that exist on the surface of the skin
Fungal diseases in plants tend to be much more serious and can threaten entire crops
Black Sigatoka is a fungal disease in bananas
It spreads through the leaves of the plant, reducing its ability to photosynthesise
The lack of photosynthesis causes parts of the leaf to die; producing black streaks
Eventually, the whole leaf dies

Question 32

What are pathogenic protoctists

Answer 32

Plasmodium falciparum is a protist that causes severe forms of malaria in humans
The parasite is spread by mosquitoes
Infected individuals experience fever, chills and fatigue
P. infestans causes the infamous potato blight
The pathogen is unusual as it has some fungal characteristics
It is transmitted via spores
The first signs of potato blight are small, dark brown marks on the leaves which quickly increase in size and number
The protist destroys potato and tomato crops leaving them completely inedible

Question 33

What are viruses

Answer 33

Viruses, which have a wide variety of shapes and sizes, all share the following biological characteristics:
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

Question 34

What are examples of Viruses

Answer 34

The tobacco mosaic virus (TMV) causes discolouring of the leaves on tobacco plants by preventing the formation of chloroplasts
The HIV virus causes AIDS
The influenza virus causes the ‘flu’