Crop plants are producers.
(a) Describe what is meant by the term producer.
(b) State three processes in the carbon cycle that involve producers.
(c) Complete the sentence about genetically modified crop plants.
Crop plants can be genetically modified to confer resistance to ………….. and …………….. .
▶️ Answer/Explanation
(a) Producers are organisms that synthesize their own organic nutrients (like glucose) through photosynthesis using sunlight energy. They form the base of food chains by converting inorganic matter into organic compounds.
(b) Three carbon cycle processes involving producers: 1) Photosynthesis (absorbs CO2), 2) Respiration (releases CO2), and 3) Decomposition (returns carbon when plants die). These maintain the carbon balance in ecosystems.
(c) Crop plants can be genetically modified to confer resistance to herbicides and pests. This modification helps plants survive chemical treatments and insect attacks, increasing agricultural yields.
(a) Fig. 3.1 is a diagram of part of the carbon cycle.
Three processes that occur in the carbon cycle are labelled Q, R and S.
(i) Complete the table by stating the names of processes Q, R and S in Fig. 3.1.
(ii) Draw one arrow on Fig. 3.1 to represent the transfer of carbon by respiration in herbivores.
(b) Carbon dioxide is one gas that causes climate change.
State the name of one other gas that causes climate change.
(c) Suggest one way that humans can increase the rate of removal of carbon dioxide from the atmosphere.
(d) Proteins contain carbon.
State two other chemical elements all proteins contain.
(e) Describe what is meant by the term carnivore.
▶️ Answer/Explanation
(a)(i)
Explanation: Process Q is photosynthesis, where plants convert CO2 into organic compounds. Process R is feeding, where carbon is transferred from plants to herbivores. Process S is respiration, releasing CO2 back into the atmosphere.
(a)(ii)
Arrow drawn from ‘carbon in herbivores’ to ‘carbon in the atmosphere’.
Explanation: Herbivores respire, releasing CO2 into the atmosphere, completing the carbon cycle.
(b) Methane (CH4)
Explanation: Methane is a potent greenhouse gas released from livestock, landfills, and fossil fuel extraction.
(c) Plant more trees.
Explanation: Trees absorb CO2 during photosynthesis, increasing carbon sequestration.
(d) Nitrogen (N) and Hydrogen (H)
Explanation: Proteins are composed of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), with some containing sulfur (S).
(e) A carnivore is an animal that obtains energy by consuming other animals.
Explanation: Carnivores are secondary or tertiary consumers in food chains, feeding exclusively on other animals.