Why are photosynthetic organisms described as the main producers of biomass for life on Earth?

They use light energy to make food, and that biomass is the starting point for almost every food chain.

Where does the carbon in a consumer's body originally come from?

From carbon dioxide that producers took in and built into glucose and other biomass during photosynthesis.

Where did the energy in a beef sandwich originally come from?

From sunlight captured by plants during photosynthesis and passed along the food chain.

Why would almost all life on Earth end if photosynthesis stopped?

No new food or biomass would be made and the oxygen used up in respiration would not be replaced.

OCR GCSE Biology A J247

Cell Level Systems

Topic overview Microscopy, and sub-cellular structures DNA structure: polymer, double helix and nucleotides Protein synthesis and the triplet code Enzyme action, and investigating enzymes Cellular respiration as an exothermic process Aerobic and anaerobic respiration compared Synthesis and breakdown of carbohydrates, proteins and lipids Photosynthesis: producers and the process Photosynthesis as endothermic, and investigating it Limiting factors in photosynthesis

Community Level Systems

Topic overview Cycling materials, and the role of microorganisms The carbon and water cycles, and decomposition Levels of organisation, and abiotic and biotic factors Interdependence, competition and trophic levels Pyramids of biomass and the efficiency of transfer

Genes, Inheritance and Selection

Topic overview Genetic terms, and the genome Genome, environment and mutations How genetic variants influence phenotype Asexual and sexual reproduction compared Haploid, diploid and meiosis Single gene inheritance and Punnett squares Sex determination, multiple genes and Mendel's work Variation within a population, and classification Natural selection and evolution Evidence for evolution, and the work of Darwin and Wallace

Global Challenges

Topic overview Field investigations, and human impact on ecosystems Maintaining biodiversity, and evidence for environmental change Food security, agricultural and biotechnological solutions Selective breeding and genetic engineering Health, disease, and types of disease Interactions between diseases, and how they spread Reducing the spread of disease, and named examples Physical and chemical plant defences Detecting plant disease; white blood cells and platelets Non-specific defences and the immune system Monoclonal antibodies and their uses Vaccines, medicines and aseptic technique Developing new medicines, and non-communicable disease Treating cardiovascular disease, and lifestyle factors Cancer, and the use of stem cells in medicine Gene technology in medicine, and the human genome

Organism Level Systems

Topic overview The nervous system and coordinated responses The reflex arc The eye and its common defects The structure and function of the brain Investigating and treating the brain Hormonal coordination, thyroxine and adrenaline Hormones in reproduction and the menstrual cycle Contraception and treating infertility Plant hormones and their commercial uses Homeostasis, and the skin in temperature control Insulin and glucagon in blood sugar control Type 1 and type 2 diabetes Osmotic changes in body fluids, and the kidneys The kidney tubule and the effect of ADH Responding to temperature and osmotic challenges

Scaling Up

Topic overview Diffusion, osmosis and active transport Mitosis, the cell cycle and cell differentiation Stem cells in animals and meristems in plants Surface area to volume ratio and exchange surfaces The circulatory system, the heart and blood vessels Red blood cells and plasma Root hair cells, transpiration and translocation Xylem and phloem Factors affecting water uptake, and the potometer

Cell Level Systems

Photosynthesis: producers and the process

3 things to know
Paper 3

Overview

Why photosynthetic organisms are the main producers of biomass, algae and phytoplankton as producers, where the carbon and energy in consumers come from, why life depends on photosynthesis and food chains start with producers, the word equation, chloroplasts and chlorophyll, where the reactants come from, the two stages, and what happens to the glucose made.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

Give the word equation for photosynthesis, say where the plant obtains each reactant, and describe its two stages in order.

Key term

What is meant by biomass?

Key term

Name two groups of photosynthetic producers other than land plants.

Questions from this subtopic

Each one with the model answer underneath.

1
Why are photosynthetic organisms described as the main producers of biomass for life on Earth?
Model answer
They use light energy to make food, and that biomass is the starting point for almost every food chain.
2
Where does the carbon in a consumer's body originally come from?
Model answer
From carbon dioxide that producers took in and built into glucose and other biomass during photosynthesis.
3
What is meant by biomass?
Model answer
The mass of living material present in an organism.
4
Name two groups of photosynthetic producers other than land plants.
Model answer
Algae and phytoplankton.
5
Where did the energy in a beef sandwich originally come from?
Model answer
From sunlight captured by plants during photosynthesis and passed along the food chain.
6
Why would almost all life on Earth end if photosynthesis stopped?
Model answer
No new food or biomass would be made and the oxygen used up in respiration would not be replaced.

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Cell Level Systems

Community Level Systems

Genes, Inheritance and Selection

Global Challenges

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Algae and .

phytoplanktonfungianimals

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AThe blood becomes too dilute.

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Egestion means passing out of undigested food as faeces.

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