CBSE Class 10 Biology Our Environment MCQs Set D

Question: Offspring formed by asexual method of reproduction have greater similarity among themselves because
a) asexual reproduction involves only one parent
b) asexual reproduction does not involve gametes
c) asexual reproduction occurs before sexual reproduction
d) asexual reproduction occurs after sexual reproduction
Answer: a

Question: During adolescence, several changes occur in the human body. Mark one change associated with sexual maturation in boys.
a) loss of milk teeth
b) increase in height
c) cracking of voice
d) weight gain
Answer: c

Question: The harmful chemical which is accumulating in human beings through food chain is
a) BHC
b) DDT
c) Abscisic acid
d) CFC
Answer: b

Question: In a food chain third trophic level is always occupied by
a) Carnivores
b) Herbivores
c) Producers
d) Decomposers
Answer: a

Question: The copying of DNA occurs during
a) cell formation
b) cell division
c) protein synthesis
d) reproduction
Answer: b

Question: An environment friendly practice is
a) Using CFLs at homes and offices
b) Using car to go to nearby places
c) Using AC in every room
d) Burning plastics
Answer: a

Question: The main cause of variations among organisms during sexual reproduction is
a) Errors in copying DNA
b) Errors in RNA
c) Errors in both RNA and DNA
d) Genetic drift
Answer: a

Question: The cleaners of nature are
a) Producers
b) Consumers
c) Herbivores
d) Decomposers
Answer: d

Question: The biotic components of an ecosystem consist of
a) Plants and animals
b) Algae and fungi
c) Producers, consumers & decomposers
d) Air, water, soil
Answer: c

Question: The north pole of earth’s magnet is in the:
a) geographical south
b) geographical east
c) geographical west
d) geographical north
Answer: a

Question: The function of testes at puberty does not include:
a) formation of germ cells
b) secretion of testosterone
c) development of placenta
d) secretion of estrogen
Answer: c

Question: The reproduction is essential for population of a species
a) to decrease its number
b) to increase its number
c) for its survival
d) to become extinct
Answer: b

Question: The correct sequence of events of sexual reproduction in a flower is:
a) pollination, fertilisation, seedling, embryo
b) seedling, embryo, fertilisation, pollination
c) pollination, fertilisation, embryo, seedling
d) embryo, seedling, pollination, fertilisation
Answer: c

Question: In human males, the testes lie in the scrotum, because it helps in the
a) process of mating
b) formation of sperm
c) easy transfer of gametes
d) all the above
Answer: b

Question: Which of the following limits the number of trophic levels in a food chain
a) Water
b) Polluted air and water
c) Deficient food supply
d) Decrease in energy at higher trophic levels
Answer: d

Question: Carnivores represent
a) Primary consumers
b) Reducers
c) Phytoplanktons
d) Secondary and tertiary consumers
Answer: d

Question: In human females, an event that reflects onset of reproductive phase is
a) growth of body
b) changes in hair pattern
c) change in voice
d) menstruation
Answer: d

Question: In a flower, the parts that produce male and female gametes (germ cells) are
a) stamen and anther
b) filament and stigma
c) anther and ovary
d) stamen and style
Answer: c

Question: Fertilisation is the process of
a) transfer of male gamete to female gamete
b) fusion of nuclei of male and female gamete
c) adhesion of male and female reproductive organs
d) the formation of gametes by a reproductive organ
Answer: b

Question: Ozone hole may cause
a) Mutations
b) Global warming
c) Skin cancer
d) All of these
Answer: d

Question: In the list of organisms given below, those that reproduce by the asexual method are
a) (ii) and (iv)
b) (i), (iii) and (iv)
c) (i) and (iv)
d) (ii), (iii) and (iv)
Answer: b

Question: What will happen if deer is missing in the food chain given below?
Grass → Deer → Tiger
a) The population of tiger increases
b) The population of grass decreases
c) Tiger will start eating grass
d) The population of tiger decreases and the population of grass increases
Answer: d

Question: Which of the following could be incinerated
a) Paper
b) Medicine bottles
c) Needle of syringe
d) All of these
Answer: a

Question: Which group of waste materials can be classified as non-biodegradable?
a) Plant waste, used tea bags
b) Polyethene bags, plastic toys
c) Used tea bags, paper straw
d) Old clothes, broken footwear
Answer: c

Question: The main reason for increase in temperature in a glass house is
a) Sunlight is completely absorbed by plants in the glass house
b) Radiation fails to escape from the glass house completely
c) Plants do not utilize sunlight in a glass house
d) Plants produce heat inside the glass house
Answer: b

Question: DDT is a non-biodegradable chemical. When it enters a food chain, it accumulates at each trophic level. This phenomenon is called –
a) Eutrophication
b) Chemical amplification
c) Biomagnification
d) Chemical magnification
Answer: c

Question: In the given pyramid diagram showing trophic levels, at which trophic level is maximum energy available?
a) T4
b) T2
c) T1
d) T3
Answer: c

Question: The decomposers in an ecosystem:
a) Convert organic material to inorganic forms
b) Convert inorganic material to simpler forms
c) Convert inorganic material into organic compound
d) Do not break down organic compound
Answer: a

Question: Which of the following constitutes a food chain?
a) Grass, goat and human
b) Goat, crow and elephant
c) Grass, fish and zebra
d) Grass, wheat and apple
Answer: a

Question: Which of the following aquatic organisms will have the maximum amount of pesticide per gram of body mass in a highly pesticide polluted pond?
a) Lotus
b) Fishes
c) Spirogyra
d) Zooplanktons
Answer: b

Question: The decomposers in a food web use energy primarily for:
a) Themselves
b) Reflection from Earth's surface
c) Natural biocomposting
d) It is lost as heat
Answer: d

Question: Organisms which synthesise carbohydrates from inorganic compounds using radiant energy are called
a) Decomposers
b) Producers
c) Herbivores
d) Carnivores
Answer: b

Question: Abundance of coliform bacteria in a water body is indicative of pollution from:
a) Petroleum refinery
b) Metal smelter
c) Fertilizer factory
d) Domestic sewage
Answer: d

Question: What is incorrect about recycling?
a) Saves precious resources
b) Requires stable market
c) Improves efficiency of treatment processes
d) Increases the need for mining virgin materials
Answer: d

Question: Which of the following pair is incorrectly matched?
a) Autotrophs – Fungi
b) Primary consumers – Zooplankton
c) Secondary consumers – Fishes
d) Decomposers – Fungi
Answer: a

Question: Biodegradable wastes include
a) Aluminium foils
b) Glass bottles
c) Pesticides
d) Wood shavings
Answer: d

Question: Read the following statements:
(I) Energy transfer in the biotic world always proceeds from the autotrophs.
(II) Energy flow is unidirectional.
(III) Energy availability is maximum at the tertiary level.
(IV) There is loss of energy from one trophic level to the other.
Select the relevant statements for the forest ecosystem:
a) I, II and IV
b) I, II and III
c) I, III and IV
d) II, III and IV
Answer: a

True Or False :

Question: Biodegradable wastes should be separated and kept in blue colour bins for garbage collectors.
Answer: False

Question: Human population and technology are having a destructive impact on the biosphere.
Answer: True

Question: Secondary consumers in a food chain are always carnivores.
Answer: True

Question: Carbon dioxide causes depletion of ozone layer thereby allowing more UV-radiations to reach the earth.
Answer: False

Question: Earth is kept warm due to green house flux.
Answer: True

Assertion-Reason type Questions :

For question numbers 1 and 2 two statements are given-one labeled as Assertion (A) and the other labeled
Reason (R). Select the correct Answer to these questions from the codes (a), (b), (c) and (d) as given below:
a) Both ‘A’ and ‘R’ are true and ‘R’ is correct explanation of the assertion.
b) Both ‘A’ and ‘R’ are true but ‘R’ is not correct explanation of the assertion.
c) ‘A’ is true but ‘R’ is false.
d) ‘A’ is false but ‘R’ is true.

Question:
Assertion: DNA is deoxyribonucleic acid.
Reason: DNA transfers genetic characteristics from parents to offsprings.
Answer: b

Question:
Assertion: There are three types of RNA, t-RNA, m-RNA and r-RNA.
Reason: RNA does not undergo replication.
Answer: b

For question numbers 1 and 2 two statements are given-one labeled as Assertion (A) and the other labeled
Reason (R). Select the correct Answer: to these questions from the codes a), b), c) and d) as given below:
a) Both ‘A’ and ‘R’ are true and ‘R’ is correct explanation of the assertion.
b) Both ‘A’ and ‘R’ are true but ‘R’ is not correct explanation of the assertion.
c) ‘A’ is true but ‘R’ is false.
d) ‘A’ is false but ‘R’ is true.

Question:
Assertion: Pollination is different from fertilisation.
Reason: The process of transfer of pollens from anther to stigma is called pollination which takes place in plants.
Answer: b

Question:
Assertion: Pistil is male reproductive part of flower.
Reason: Pollen grain land on stigma and germinate.
Answer: d

For question numbers 1 and 2 two statements are given-one labeled as Assertion (A) and the other labeled
Reason (R). Select the correct Answer: to these questions from the codes a), b), c) and d) as given below:
a) Both ‘A’ and ‘R’ are true and ‘R’ is correct explanation of the assertion.
b) Both ‘A’ and ‘R’ are true but ‘R’ is not correct explanation of the assertion.
c) ‘A’ is true but ‘R’ is false.
d) ‘A’ is false but ‘R’ is true.

Question:
Assertion: Cell division is a type of reproduction in unicellular organisms.
Reason: It leads to formation of two daughter cells where means is to produce more individuals.
Answer: a

Question:
Assertion: Spores are formed in sporangia.
Reason: Spores grow into separate individuals in moist conditions.
Answer: a

In the following question, a statement of Assertion (A) is followed by a statement of Reason (R). Answer: these questions by selecting appropriate option given below:
(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A)
(c) Assertion (A) is true but Reason (R) is false.
(d) Assertion (A) is false but Reason (R) is true.

Question:
Assertion (A): Ozone is both beneficial and damaging.
Reason (R): We should stop the release of chlorofluorocarbons to protect the ozone.
Answer: b

Question:
Assertion (A): Biomagnification is caused due to the accumulation of biodegradable toxicants in organisms at each successive trophic level.
Reason (R): Biomagnification leads to the maximum accumulation of chemicals in small fishes.
Answer: c

Question:
Assertion (A): Autotrophs are present at the first trophic level.
Reason (R): Consumers or heterotrophs fix energy making it available for autotrophs.
Answer: c

Question:
Assertion (A): The crown fires are most destructive as they burn the tree top.
Reason (R): Due to crown fire the temperature of that area may rise upto 700° C.
Answer: a

Question:
Assertion (A): Polythene bags and plastic containers are non-biodegradable substance.
Reason (R): They can be broken down by micro-organisms in natural simple harmless substances.
Answer: c