State the equation used to calculate the efficiency of a biomass transfer.

Efficiency is the biomass transferred divided by the biomass intake, multiplied by 100.

A bullock takes in 45 000 kJ of biomass and adds 2 700 kJ to its own tissues. Calculate the efficiency of the transfer.

The efficiency of the transfer is 6.0%.

A fish farm supplies 1 500 kg of feed and the stock gains 375 kg. Calculate the percentage efficiency of the transfer.

The efficiency of the transfer is 25%.

Give three reasons why not all of the biomass of a producer is transferred to a primary consumer.

Some parts of the plant are never eaten, some of what is eaten is not digested and is egested in faeces, and much of what is absorbed is respired and lost as heat.

OCR A-Level Biology B H422

The Developing Cell: Cell Division and Cell Differentiation

Topic overview The cell cycle and mitosis Apoptosis in growth and repair Stem cells and cell differentiation

The Developing Individual: Meiosis, Growth and Development

Topic overview Meiosis, haploid gametes and genetic variation The stages of meiosis Antenatal care and diet in pregnancy Alcohol, smoking and monitoring fetal growth Prenatal screening and karyotypes

The Development of Species: Evolution and Classification

Topic overview Classification and the species concept Evidence for classification and DNA barcoding Phylogenetic trees, hominids and the evolution of language Human adaptations, natural selection and evolution Plant adaptations and how they are investigated Measuring biodiversity and genetic diversity

Cells and Microscopy

Topic overview Microscopy and the cell theory Blood smears, staining and microscope drawings Blood cells and their structure Magnification and measuring cells Haemocytometer cell counts and dilutions Flow cytometry in blood analysis Ultrastructure of the animal cell Plant and prokaryotic cells Membrane lipids and the fluid mosaic model Movement of molecules across membranes The roles of membranes and the secretion of proteins

Water and Its Importance in Plants and Animals

Topic overview The properties of water Water as a transport medium and the composition of body fluids Detecting and measuring sugars and proteins Monomers, polymers and the carbohydrates Osmosis and water potential

Proteins and Enzymes

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Nucleic Acids

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Patterns of Inheritance

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Population Genetics and Epigenetics

Topic overview Natural selection, sickle cell and malaria The Hardy-Weinberg principle Genetic drift, the founder effect and speciation Epigenetics and gene expression

Gene Technologies

Topic overview Post-Transcriptional Editing of mRNA Genetic modification of bacteria and insulin production The polymerase chain reaction and gel electrophoresis Haplotypes, SNPs, VNTRs and genetic engineering in eukaryotes Gene therapy and RNA interference

The Principles and Importance of Homeostasis

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The Hormonal Control of Blood Glucose and the Management of Diabetes

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Kidney Functions and Malfunctions

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Respiratory Diseases and Treatment

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Cellular Respiration

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Metabolism and Exercise

Topic overview The consequences of exercise on the body Aerobic fitness and VO₂ max Training, F.I.T.T. factors and investigating fitness Enhancing athletic performance Haemoglobin and the transport of oxygen Oxygen dissociation curves of different respiratory pigments Oxygen deficit and oxygen debt The structure of skeletal muscle The sliding filament theory of muscle contraction

Pathogenic Microorganisms

Topic overview How pathogens cause communicable disease Tuberculosis HIV, AIDS and the structure of the virus Identifying bacteria: Gram staining and culture Epidemiology: incidence, prevalence and mortality Notifiable diseases and the control of HIV and TB

The Immune System

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Controlling Communicable Diseases

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Photosynthesis, Food Production and Management of the Environment

Topic overview Chloroplast ultrastructure and photosynthetic pigments The light-dependent stage of photosynthesis The Calvin cycle Investigating the factors affecting photosynthesis The Hill reaction and DCPIP Using TP and GP to build carbohydrates, lipids and amino acids The compensation point and crop production Microorganisms, the nitrogen cycle and biosensors Biomass transfer and efficiency in food production Ruminants in the human food chain Farms as ecosystems and the conflict with conservation Deflected succession and measuring biodiversity

The Impact of Population Increase

Topic overview Birth rate, death rate and demographic change Human impact on ecosystems and biodiversity The importance and measurement of species biodiversity Global food security and sustainable food production

Planning and Implementing Practical Work

Topic overview Designing an investigation and controlling variables Choosing apparatus and judging whether a method will work Implementing: apparatus, units and recording results

Analysing and Evaluating Practical Results

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Practical Skills, Apparatus and Techniques

Topic overview Investigative approaches and working safely Following instructions, recording and presenting data Research, referencing and processing data with software Measuring mass, volume, time, temperature, length and pH Colorimeters and potometers Laboratory glassware and serial dilutions Light microscopy, graticules and biological drawing Qualitative reagents for biological molecules Chromatography and electrophoresis Aseptic technique and dissection Whole-organism responses, fieldwork sampling and data logging

Fertility and Assisted Reproduction

Topic overview The urinogenital systems and gonad histology Gametogenesis and the structure of the gametes Hormonal control of gametogenesis and the menstrual cycle Fertilisation and pregnancy testing The causes and issues of infertility Assisted reproduction techniques

The Effects of Ageing on the Reproductive System

Topic overview Ageing and the female reproductive system Managing the menopause Ageing and the male urinogenital system

Plant Reproduction

Topic overview The control of flowering Adaptations of flowers for pollination Fertilisation, seed formation and germination Cereals as staple foods

The Nervous System and the Identification and Consequences of Damage

Topic overview Organisation of the nervous system and nervous tissue The structure and function of the human brain The structure of motor, sensory and relay neurones Resting potential and the action potential Synapses and the integration of responses Reflexes, reaction times and their investigation Brain scans and the consequences of nervous system damage Drugs, brain function and dependency

Monitoring Visual Function

Topic overview The structure of the eye The retina and its role as a transducer Assessing visual function by routine eye tests

The Effect of Ageing on the Nervous System

Topic overview Alzheimer's disease: symptoms and causes The effects of ageing on the senses and memory Investigating ageing, reaction times and memory

The Heart and Monitoring Heart Function

Topic overview The need for a mass transport system Structure and dissection of the mammalian heart The cardiac cycle Initiation and coordination of the heartbeat Heart rate, pulse rate and cardiac output Electrocardiograms and emergency cardiac treatment

Transport Systems in Mammals

Topic overview The closed double circulatory system Blood vessels and their microscopic structure Tissue fluid and capillary exchange Measuring and interpreting blood pressure

Gas Exchange in Mammals and Plants

Topic overview Tissues of the mammalian gas exchange system Gas exchange in the alveoli Pulmonary ventilation and lung volumes Expired air resuscitation Gas exchange and stomata in terrestrial plants

Transport Systems in Plants

Topic overview The need for transport systems in plants Vascular tissue in roots, stems and leaves Water uptake and movement through the plant Transpiration and Its Measurement Translocation in the Phloem

Photosynthesis, Food Production and Management of the Environment

Biomass transfer and efficiency in food production

3 things to know
Components 01, 02 and 03

Overview

Recall questions on biomass and dry mass, calculating the efficiency of biomass transfer, why biomass is lost between trophic levels, the length of food chains, farmed fish compared with beef cattle, the sustainability of salmon farming, feeding maize to cattle, and rearing livestock indoors.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Numbers

What is biomass, how is the efficiency of a biomass transfer calculated, why is energy lost as heat at each trophic level, and roughly what percentage is transferred?

Key term

What is meant by biomass in an ecological context?

Key term

Why is dry mass rather than fresh mass used when measuring biomass?

Questions from this subtopic

Each one with the model answer underneath.

1
What is meant by biomass in an ecological context?
Model answer
Biomass is the mass of living material present, usually expressed as dry mass per unit area.
2
Why is dry mass rather than fresh mass used when measuring biomass?
Model answer
Water content varies widely between organisms and from day to day, so only dry mass gives a comparable measure of the organic material present.
3
State the equation used to calculate the efficiency of a biomass transfer.
Model answer
Efficiency is the biomass transferred divided by the biomass intake, multiplied by 100.
4
A bullock takes in 45 000 kJ of biomass and adds 2 700 kJ to its own tissues. Calculate the efficiency of the transfer.
Model answer
The efficiency of the transfer is 6.0%.
5
A fish farm supplies 1 500 kg of feed and the stock gains 375 kg. Calculate the percentage efficiency of the transfer.
Model answer
The efficiency of the transfer is 25%.
6
Give three reasons why not all of the biomass of a producer is transferred to a primary consumer.
Model answer
Some parts of the plant are never eaten, some of what is eaten is not digested and is egested in faeces, and much of what is absorbed is respired and lost as heat.

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The Developing Cell: Cell Division and Cell Differentiation

The Developing Individual: Meiosis, Growth and Development

The Development of Species: Evolution and Classification

Cells and Microscopy

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