28: Biodiversity

Question 1

State the meaning of biodiversity.

Answer 1

Biodiversity is the wide variety of life forms on earth.

Question 2

State 4 benefits of classifying organisms.

Answer 2

1. We can study organisms in a systematic way.
2. We can identify an organism more easily by matching it with the characteristics of one of the groups.
3. We can understand the evolutionary history of organisms.
4. We can make predictions.

Question 3

State the definition of species.

Answer 3

Organisms belonging to the same species are potentially capable of interbreeding to produce fertile offspring.

Question 4

State two features of organisms belonging to the same species in the classification.

Answer 4

They have similar structural features and genetic materials.

Question 5

List the classification divisions in Linneaeus’ system in increasing order of similarity.

Answer 5

Kingdom, phylum, class, order, family, genus, species

Question 6

State the meaning of binomial nomenclature when naming organisms.

Answer 6

Binomial nomenclature is a way to name organisms with a scientific name consisting of two Latin words. The first word is the genus name while the second word is the species name.

Question 7

List two formatting features of the binomial nomenclature.

Answer 7

1. The first word (genus name) begins with a capital letter while the second word (species name) begins with a small letter.
2. The scientific name is italicised in print and underlined in handwriting.

Question 8

Name all the organism kingdoms in the order of their proposal.

Answer 8

Plantae and Animalia, Protista, Prokaryota, Fungi, Eubacteria and Archaebacteria (replacing Prokaryota)

Question 9

List two differences between fungi and plants that led to the formation of kingdom Fungi.

Answer 9

1. The composition of cell wall of fungi is different from that of plants.
2. Fungi do not carry out photosynthesis unlike plants.

Question 10

Name all the kingdoms according to domain.

Answer 10

Domain Bacteria: Kingdom Eubacteria
Domain Archaea: Kingdom Archaebacteria
Domain Eukarya: Kingdoms Plantae, Animalia, Protista, Fungi

Question 11

State the relationship between common ancestors and common classification levels of two different organisms.

Answer 11

Organisms with a more recent common ancestor will share a lower common classification level.

Question 12

State one assumption when studying the phylogenetic relationships between organisms using gene sequencing.

Answer 12

The more similar the genetic material between two organisms, the closer their phylogenetic relationship.

Question 13

State the major features of bacteria.

Answer 13

Bacteria are unicellular prokaryotes. They have no true nucleus and their genetic material is a circular DNA lying free in the cytoplasm.
They have no membrane-bound organelles.
They have a cell wall made of peptidoglycan. Some are enclosed by a capsule and some have a hair-like flagellum for locomotion.

Question 14

Name three shapes of bacteria.

Answer 14

Rod-shaped, spherical, spiral

Question 15

Explain why archaebacteria were once considered as bacteria but later separated into its own kingdom.

Answer 15

Archaebacteria are unicellular prokaryotes like bacteria. Since they have similar appearances, they were considered as bacteria. However, archaebacteria are discovered to be more closely related to eukaryotes than to bacteria after biochemical and genetic analyses.

Question 16

State the major features of archaebacteria.

Answer 16

Most of them have a cell wall but their chemical composition is unique.
The lipid that makes up the cell membrane is different from that of other organisms.
Many archaebacteria live in extreme environments that may be similar to the conditions on primitive earth.

Question 17

List 3 examples of extreme environments which archaebacteria live in.

Answer 17

1. Hot and acidic environment, such as hot sulphur spring.
2. Very salty environment, such as the Dead Sea.
3. Environments lacking oxygen, such as swamps and digestive tracts of animals.

Question 18

State the major features of protists.

Answer 18

They are eukaryotes and most are unicellular. They have a true nucleus and other membrane-bound organelles.
They live mainly in water or inside other organisms.

Question 19

List and explain 3 main groups of protists.

Answer 19

1. Protozoans, they are animal-like, eg. can move from place to place.
2. Algae, they are plant-like, eg. have chloroplasts and make their own food by photosynthesis.
3. Slime mould: They exist as unicellular Amoeba-like cells in feeding stage and look like fungi in reproductive stage.

Question 20

State the major features of fungi.

Answer 20

Most fungi are multicellular. They are made up of thread-like hyphae which may interweave to form mycelium. Part of the mycelium may form a specialised fruiting body that releases spores for reproduction.
They have a cell wall not made of cellulose.
They have no chlorophyll and cannot make their own food.

Question 21

List 3 different groups of fungi.

Answer 21

1. Fungi carrying out saprophytic nutrition, feeding on dead organisms or non-living organic matter.
2. Fungi carrying out parasitic nutrition, obtaining food from their living host.
3. Unicellular fungi which absorbs sugars from the surroundings for growth.

Question 22

State the major features of plants.

Answer 22

Plants are autotrophs. They have chlorophyll for photosynthesis.
Plant cells have a cell wall compared of cellulose.
Plants cannot move from place to place.

Question 23

List 3 major classifications within plants.

Answer 23

Plants can be divided into vascular plants and non-vascular plants.
Vascular plants can be divided into ferns, conifers, and flowering plants.
Flowering plants can be divided into monocotyledonous plants and dicotyledonous plants.

Question 24

State the major features of non-vascular plants.

Answer 24

Non-vascular plants have mo vascular tissues. They have simple stems and leaves, but no true roots. Most of them are small and grow in damp shady places.
They have rhizoids for anchorage and for absorption of water and minerals.
They have chlorophyll for photosynthesis and produce spores for reproduction.

Question 25

State the meaning of true roots.

Answer 25

True roots are the roots that develop from the radicle of an embryo during seed germination.

Question 26

State the major features of vascular plants.

Answer 26

Vascular plants have vascular tissues. They have true roots, stems, and leaves. Most of them are well adapted to living in dry places.

Question 27

State the major features of ferns.

Answer 27

Most ferns have large and feathery leaves. The young leaves are curled. They produce **spores** instead of seeds for reproduction. The spore-bearing structures are usually located on the underside of the leaves.

Question 28

State the major features of conifers.

Answer 28

Conifers are trees or shrubs producing **cones**, which carry seeds for reproduction. They are called **naked seeds** as they are not enclosed in fruits. Most conifers have needle-shaped leaves.

Question 29

State the major features of flowering plants.

Answer 29

Flowering plants produce flowers and seeds which are protected inside fruits. They can be divided into monocotyledonous and dicotyledonous plants.

Question 30

List 3 differences between monocots and dicots.

Answer 30

1. Monocots have 1 cotyledon in seeds while dicots have 2 cotyledons in seeds. 2. Monocots have parallel leaf venation while dicots have net venation. 3. Monocots have flowers with petals usually in multiples of 3 while dicots have flowers with petals usually in multiples of 4 or 5.

Question 31

State the major features of animals.

Answer 31

Animals are heterotrophs which obtain food from other organisms. Animal cells do not have a cell wall. Most animals can move freely from place to place during certain stages of their lives.

Question 32

List 2 major classifications within animals.

Answer 32

Animals can be divided into vertebrates and invertebrates. Vertebrates can be divided into fish, amphibians, reptiles, birds, and mammals.

Question 33

List 5 groups of invertebrates.

Answer 33

Hollow-bodied animals, segmented worms, soft-bodied animals, joint-legged animals, spiny-skinned animals.

Question 34

State the major features of hollow-bodied animals.

Answer 34

They have **tentacles** with stinging cells for catching small prey. They have only one body opening which serves as both the mouth and anus.

Question 35

List 3 examples of hollow-bodied animals.

Answer 35

Jellyfish, corals, sea anemones

Question 36

State the major features of segmented worms.

Answer 36

They have a tube-like body with a lot of segments. They have **chaetae** for movement.

Question 37

List 2 examples of segmented worms.

Answer 37

Earthworms, sandworms

Question 38

State the major features of soft-bodied animals.

Answer 38

They have a soft body. They have **muscular foot** for movement. Some are protected by a hard shell.

Question 39

List 4 examples of soft-bodied animals.

Answer 39

Snails, clams, squids, octopuses

Question 40

State the major features of joint-legged animals.

Answer 40

They make up about 75% of all animals. They have **segmented** bodied covered by **exoskeleton**. They have 3 or 4 pairs of **jointed legs**. They may have antennae, mouth parts, wings, and compound eyes.

Question 41

List 2 examples of animal types and 6 examples of joint-legged animals.

Answer 41

Insects: bees, ants Crustaceans: shrimps, lobsters, crabs Spiders

Question 42

State the major features of spiny-skinned animals.

Answer 42

They have spines on the body surface. They have numerous **tube feet** for movement.

Question 43

List 3 examples of spiny-skinned animals.

Answer 43

Sea urchins, sea cucumbers, starfish

Question 44

State the body and reproductive features of fish.

Answer 44

Body features: they have gills for gas exchange, fins for balance and movement, and most have slimy scales covering their bodies. Reproduction method: Most carry out **external fertilisation** and lay eggs in water.

Question 45

State the body and reproductive features of amphibians.

Answer 45

Body features: They use lungs and the surface of skin to carry out gas exchange. Their larvae use gills for gas exchange. Most have 4 limbs. Their bodies are covered with **moist naked skin**. Reproduction method: External fertilisation, most lay eggs in water.

Question 46

State the body and reproductive features of reptiles.

Answer 46

Body features: They have lungs for gas exchange and **dry, hard scales** covering their skin. Most have 4 limbs. Reproduction method: Internal fertilisation, most lay eggs with hard shells.

Question 47

State the body and reproductive features of birds.

Answer 47

Body features: They have lungs fro gas exchange, wings, feathers covering their bodies, dry scales on their feet, and a beak but no teeth. Reproduction method: Internal fertilisation, most lay eggs with hard shells.

Question 48

State the body and reproductive features of mammals.

Answer 48

Body features: They have lungs for gas exchange and mammary glands. Most have hair covering their bodies and pinnae. Reproduction method: Internal fertilisation, most give birth to live young.

Question 49

List all poikilotherms which are vertebrates.

Answer 49

Fish, reptiles, amphibians

Question 50

List all homoiotherms which are vertebrates.

Answer 50

Birds, mammals

Question 51

State the meaning of a dichotomous key.

Answer 51

A dichotomous key is a tool used to identify organisms, which provides two alternative features at each step so the organism can be identified step by step.