Question 21
Which of the following neurons may not have myelin sheath?
Options
A) Effector cells
B) Intermediate neurons
C) Motor neurons
D) Sensory neurons
The correct answer is A.
Question 22
Which of the following is an effector organ?
Options
A) Tongue
B) Skin
C) Nose bridge
D) Ear glands
The correct answer is B.
Explanation:
Effector organs are smooth muscle, cardiac muscle and glands that respond to nerve impulses from the central nervous system without conscious thought. They are part of the automatic, or involuntary, nervous system, along with receptors, afferent nerves and efferent nerves.
Question 23
During sexual reproduction in Paramecium, how many times does the zygote divide to produce eight nuclei?
Options
A) 1
B) 2
C) 3
D) 4
The correct answer is C.
Question 24
The examples of autotrophic organisms include the following except
Options
A) Euglena
B) Chlamydomonas
C) Hydra
D) Spirogyra
The correct answer is C.
Question 25
Which of the following organisms feeds both autotrophically and heterotrophically?
Options
A) Hydra
B) Paramecium
C) Mucor
D) Euglena
The correct answer is D.
Question 26
Siphons and gills are structures in aquatic organisms used for
Options
A) gaseous exchange
B) buoyancy
C) excretion
D) movement
The correct answer is A.
Question 27
The first step in carrying out ecological studies in a terrestrial habitat is
Options
A) quadrat sampling
B) mapping the area
C) collection of organisms
D) measuring abiotic factors
The correct answer is B.
Question 28
Which of the following components of an ecosystem does not contribute to the biomass of the system?
Options
A) Producers
B) Consumers
C) Micro-organisms
D) Habitat
The correct answer is D.
Question 29
The group of several populations that interact and share a habitat, form
Options
A) a species
B) a community
C) an ecotype
D) a tribe
The correct answer is B.
Question 30
The physical and chemical factors which affect the life of organisms in an environment are described as
Options
A) biotic
B) edaphic
C) abiotic
D) physiographic
The correct answer is C.
Question 31
Which of these factors are common to both aquatic and terrestrial habitats?
Options
A) Light, rainfall and turbidity
B) Light, temperature and tide
C) Light, rainfall and temperature
D) Rainfall, turbidity and salinity
The correct answer is C.
Question 32
Which of these factors are common to both aquatic and terrestrial habitats?
Options
A) Light, rainfall and turbidity
B) Light, temperature and tide
C) Light, rainfall and temperature
D) Rainfall, turbidity and salinity
The correct answer is C.
Question 33
Organisms that feed essentially on plants within any ecosystem may be referred to as
Options
A) carnivores
B) herbivores
C) saprophytes
D) omnivores
The correct answer is B.
Question 34
Which of the following statements about feeding relationships is correct?
Options
A) In a food web on land, grasshopper feeds on praying mantis and on predator bugs
B) In a food chain on land, green plant is the producer
C) In an aquatic food chain mollusc larvae are the producers
D) In an aquatic food web, various copepods feed on mollusk Larvae and on sand eel
The correct answer is B.
Question 35
Which of these diseases cannot be spread by an insect?
Options
A) Cholera
B) Malaria
C) Trypanosomiasis
D) Measles
The correct answer is D.
Question 36
Air pollution can be reduced by the following methods except
Options
A) building tall factory chimneys
B) passing waste gases through filters and absorbers
C) using lead-free petrol in car
D) recycling tins, cans and bottles
The correct answer is D.
Question 37
An effective management of natural resources to ensure their continued yield from generation to generation may involve all the following except
Options
A) protection of wildlife
B) prevention of habitat destruction
C) biological control of pests
D) disposal of raw sewage into the sea
The correct answer is D.
Question 38
Which of the following orders correctly represents the trend in eutrophication?
Options
A) Lack of oxygen → Death of aquatic organisms → Massive algal growth
B) Excess nitrates and phosphates → Massive algal growth → Lack of oxygen → Death of aquatic organisms
C) Heavy mineralization → Lack of oxygen → Massive algal growth
D) Excess nitrates and phosphates → Lack of oxygen → Massive algal growth → Death of aquatic organisms
The correct answer is B.
Question 39
The following practices can contribute towards the conservation of natural resources except
Options
A) afforestation
B) deforestation
C) contour ploughing
D) establishment of Game Reserves
The correct answer is B.
Question 40
Variation is a factor which
Options
A) differentiates between individuals of the same species
B) qualifies an organism to live with others
C) enables organisms to adapt to the environment
D) states the external features of an organism