Life at Molecular, Cellular and Tissue Level

Question 1

What was considered to have evolved before plants and animals?

Answer 1

Viruses, Bacteria, Protists(algae and protozoa) and fungi

Question 2

What are pathogenic organisms

Answer 2

Disease causing organisms

Question 3

What are non-pathogenic organisms

Answer 3

Organisms that are harmless to plants and animals

Question 4

Characteristics of Viruses

Answer 4

Extremely small, can only be seen by an electron microscope
Exists in 2 states, virus(active) and virion(dormant)
Not living organisms
Are obligate intracellular parasites, only survive inside cells
Only reporduce inside living cells
Always associated with disease

Question 5

What are the different shapes of viruses

Answer 5

Polyhedral
Helical
Complex

Question 6

Structure of Viruses

Answer 6

Acellular
Simple structure containing DNA or RNA, never both at the same time
Nucleic acid is surrounded b protein coat(capsid)
Some viruses are covered in an envelope or lipid bi layer

Question 7

General characteristics of bacteria

Answer 7

Most diverse and abundant group of organisms on Earth
Inhabit practically all environments
Mostly useful, but some cause disease
Unicellular
Vary in shape
In favorable conditions, where binary fission occurs

Question 8

Definition of Binary Fission

Answer 8

An asexual process whereby a single cell divides into two identical DNA

Question 9

Structure of Bacteria

Answer 9

Unicellular
Rigid cell wall
Plasma Membrane
Prokaryotes (do not have a true nucleus)
Consists of a closed loop of DNA
Has a waxy capsule as their outermost layer
Some have flagella

Question 10

Common Characteristics of Protista

Answer 10

Eukaryotic

Live in moist environments because they have nothing to stop them from drying out

Question 11

Variable characteristics of Protists

Answer 11

unicellular or multicellular
microscopic or over 100 meters long
heterotrophs or autotrophs

Question 12

Two groups of Protista

Answer 12

Plant-like protista

Animal-like protista

Question 13

Characteristics of algae (plant-like protista)

Answer 13

Simple aquatic eukaryotes
contain chlorophyll
Autotrophic
Release large amounts of oxygen
Mostly free-floating
Reproduce asexually

Question 14

3 times of algae groups

Answer 14

Green algae
Brown algae
Red algae

Question 15

What are animal-like protists called

Answer 15

Protozoans

Question 16

What do all protozoans have

Answer 16

Unicellular
heterotrophs
Swim around looking for food

Question 17

What is Plankton

Answer 17

Numerous micro-organisms floating in currents of the open oceans.

Question 18

What two can plankton be divided into

Answer 18

Phytoplankton and Zooplankton

Question 19

Definition of Phytoplankton

Answer 19

Plant-like protists

Question 20

Definition of Zooplankton

Answer 20

bacteria and animal-like unicellular protists

Question 21

General characteristics of fungi

Answer 21

They are everywhere, usually invisible to the naked eye
mostly free-living
Heterotrophs, as they don’t contain chlorophyll
Live in symbiotic relationships
Primary decomposers
Reporuce asexually, sexually and by budding

Question 22

Structure of Fungi

Answer 22

Multicellular eukaryotes
Conists of mass hyphae enclosed by a rigid cell wall of chitin and glucan
Hyphae branch makes up the thallus or undifferentiated vegetative body

Question 23

Functions of Micro-Organisms in environment

Answer 23

Plant-degraders
Micro-regulators
Regeneration of oxygen
Nitrogen Transformers
Biological control agents

Question 24

What is Symbiosis

Answer 24

Symbiosis is a close association between different species

Question 25

What are the three different types of symbiosis and explain each

Answer 25

Mutualism- both species benefit Parasitism-one benefits, the other is harmed Commensalism- neither are harmed, but one benefits

Question 26

Economic uses of bacteria

Answer 26

``` Degrade herbicides Eat or neutralize toxic waste Synthesise riboflavin Separates the fibers Replace pesticides Decompose sewage wastes Produce food by fermentation Make probiotics ```

Question 27

Economic uses of Algae

Answer 27

``` Used as gelling agents in food products Thickeneing and stabilizing agents Make agar plates Plant growth regulators Iodine Natural pigments Nutrient extracts ```

Question 28

Economic uses of Fungi

Answer 28

Food source Used for biological compounds To produce drugs For fermentation processes

Question 29

Example of a disease associated with a virus, bacteria, protozoan, fungi

Answer 29

HIV/AIDS, TB, Malaria, Candidiasis thrush

Question 30

What are the immune response by plants

Answer 30

Plants recognise the shape of pathogens Produce salicylic acid Activate resistance genes Self-destruct

Question 31

Immune response by animals

Answer 31

First line of defense is the skin, prevents pathogens from entering Second line of defense, is inflammation and fever to destroy germs to prevent spreading Immune system is activated

Question 32

Is the immune system an active or passive response to infection

Answer 32

Active

Question 33

What are the two main measures involved

Answer 33

Destruction of invading germs and holding a memory of this response

Question 34

Two groups of white blood cells

Answer 34

Lymphocytes and Phagocytes

Question 35

What are the 2 types of lymphocytes

Answer 35

B and T lymphocytes

Question 36

How do B lymphocytes destroy germs

Answer 36

B lymphocytes recognize the antigens on a germs surface as non-human Once identified, the B lymphocyte replicates itself rapidly These lymphocytes are then stimulated to produce antibodies (immunoglobulins) These antibodies then combine with the antigens and destroy or neutralize germs Some B lymphocytes stay in the lymph gland as memory cells

Question 37

What is the purpose of memory cells

Answer 37

If the antigen is encountered again, the lymphocytes can launch a faster attack to kill the germ before it multiplies

Question 38

What is natural immunity

Answer 38

When a person has an attack of a disease so that antibodies and memory cells are produced to give protection of future attack

Question 39

What is an antigen

Answer 39

A protein or large polysaccharide molecule in the coating of a virus or bacterium which cause B lymphocytes to make antibodies

Question 40

What is an antibody

Answer 40

A protein made by B lymphocytes that destroys or neutralizes a germ

Question 41

How do antibodies destroy germs

Answer 41

Cause bacterial cells to burst Make it easier for the phagocytes to ingest the germs by labeling the germs for phagocytosis Make the germs clump together which weakens them Neutralize bacterial toxins

Question 42

Where can B lymphocytes be found

Answer 42

Tonsils, lymph glands, spleen and in the blood

Question 43

Where can T lymphocytes be found

Answer 43

Matured in the thymus ( a gland in the chest) and are then migrated to lymph organs and glands

Question 44

What is the role of T lymphocytes in the immune system

Answer 44

CD4 cells start immune response Killer T cells destroy body cells infected by viruses Suppressor cells stop the immune response once the infection is over

Question 45

How are phagocytes different from lymphocytes

Answer 45

Phagocytes are lymphocytes that can change their shape

Question 46

What is the major role of phagocytes

Answer 46

To engulf germs by phagocytosis

Question 47

How do phagocytes destroy germs

Answer 47

They move throughout the body looking for germs When a phagocyte comes into contact with a germ, it engulfs it taking it into the cell forming a phagosome. Hydrolytic enzymes in the phagosome digest and destroy the germ