AS OCR Biology A - Unit 1

AS OCR Biology A - Unit 1

HideShow resource information

2 Summary of Content

2.1 AS Units

Unit F211: Cells, Exchange and Transport

Module 1: Cells

1.1.1 Cell Structure

1.1.2 Cell Membranes

1.1.3 Cell Division, Cell Diversity and Cellular Organisation

Module 2: Exchange and Transport

1.2.1 Exchange Surfaces and Breathing

1.2.2 Transport in Animals

1.2.3 Transport in Plants

Unit F212: Molecules, Biodiversity, Food and Health

Module 1: Biological Molecules

2.1.1 Biological Molecules

2.1.2 Nucleic Acids

2.1.3 Enzymes

Module 2: Food and Health

2.2.1 Diet and Food Production

2.2.2 Health and Disease

Module 3: Biodiversity and Evolution

2.3.1 Biodiversity

2.3.2 Classification

2.3.3 Evolution

2.3.4 Maintaining Biodiversity

Unit F213: Practical Skills In Biology 1

Practical tasks

2.2 A2 Units

Unit F214: Communication, Homeostasis and Energy

Module 1: Communication and Homeostasis

4.1.1

Communication

4.1.2

Nerves

4.1.3

Hormones

Module 2: Excretion

4.2.1 Excretion

Module 3: Photosynthesis

4.3.1 Photosynthesis

Module 4: Respiration

4.4.1 Respiration

Unit F215: Control, Genomes and Environment

Module 1: Cellular Control and Variation

5.1.1

Cellular Control

5.1.2

Meiosis and Variation

Module 2: Biotechnology and Gene Technologies

5.2.1

Cloning in Plants and Animals

5.2.2

Biotechnology

5.2.3

Genomes and Gene Technologies

Module 3: Ecosystems and Sustainability

5.3.1

Ecosystems

5.3.2

Populations and Sustainability

Module 4: Responding to the Environment

5.4.1

Plant Responses

5.4.2

Animal Responses

5.4.3 Animal Behaviour

Unit F216 Practical Skills in Biology 2

Practical tasks

© OCR 2008 7

GCE Biology v2

3 Unit Content

Each unit is divided into a number of teaching modules. Within each module, the content is divided into two columns: Context and Exemplification and Assessable Learning Outcomes. Only the statements in the right hand column will be examined; statements in the left hand column are included to provide guidance on delivery. References to HSW (How Science Works) are to Appendix B. References to the GCSE Criteria for Science are to Appendix C.

3.1 AS Unit F211: Cells, Exchange and Transport

Module 1: Cells

Cells are the basic units of all living things. Organisms function because of communication and co-operation between specialised cells.

Cell division is a fundamental process, necessary for reproduction, growth and repair.

Links

GCSE Criteria for Science: 3.7(i) (c), (d); 3.9(i) (a)

1.1.1 Cell Structure

Context and exemplification

Assessable learning outcomes

The cell is the basic unit of all living things.

An understanding of how to use a light microscope is developed along with an understanding of why electron microscopes are so important in biology.

Careful observation using microscopes reveals details of cell structure and ultrastructure and provides evidence to support hypotheses regarding the roles of cells and organelles.

Candidates should be able to:

(a)

state the resolution and magnification that can be achieved by a light microscope, a transmission electron microscope and a scanning electron microscope;

(b)

explain the difference between magnification and resolution;

(c)

explain the need for staining samples for use in light microscopy and electron microscopy;

(d)

calculate the linear magnification of an image (HSW3);

(e)

describe and interpret drawings and photographs of eukaryotic cells as seen under an electron microscope and be able to recognise the following structures: nucleus, nucleolus, nuclear envelope, rough and smooth endoplasmic reticulum (ER), Golgi apparatus, ribosomes, mitochondria, lysosomes, chloroplasts, plasma (cell surface) membrane, centrioles, flagella and cilia;

(f)

outline the functions of the structures listed in (e);

8 © OCR 2008

GCE Biology v2

(g)

outline the interrelationship between the organelles involved in the production and secretion of proteins (no detail of protein synthesis is required);

(h)

explain the importance of the cytoskeleton in providing mechanical strength to cells, aiding transport within cells and enabling cell movement;

(i) compare and contrast, with the aid of diagrams and electron micrographs, the structure of prokaryotic cells and eukaryotic cells;

(j) compare and contrast, with the aid of diagrams and electron micrographs, the structure and ultrastructure of plant cells and animal cells.

1.1.2 Cell Membranes

Context and exemplification

Assessable learning outcomes

Membranes are a fundamental part of the cell.

The structure of the cell surface membrane allows cells to communicate with each other.

Understanding this ability to communicate is important as scientists increasingly make use of membrane-bound receptors as sites for the action of medicinal drugs.

Understanding how different substances enter cells is also crucial to the development of mechanisms for the administration of drugs.

Candidates should be able to:

(a)

outline the roles of membranes within cells and at the surface of cells;

(b)

state that plasma (cell surface) membranes are partially permeable barriers;

(c)

describe, with the aid of diagrams, the fluid mosaic model of membrane structure (HSW1);

(d)

describe the roles of the components of the cell membrane; phospholipids, cholesterol, glycolipids, proteins and glycoproteins;

(e)

outline the effect of changing temperature on membrane structure and permeability;

(f)

explain the term cell signaling;

(g)

explain the role of membrane-bound receptors as sites where hormones and drugs can bind;

(h)

explain what is meant by passive transport (diffusion and facilitated diffusion including the role of membrane proteins), active transport, endocytosis and exocytosis;

(i)

explain what is meant by osmosis, in terms of water potential. (No calculations of water potential will be required);

(j)

recognise and explain the effects that solutions of different water potentials can have upon plant and animal cells (HSW3).

© OCR 2008 9

GCE Biology v2

1.1.3 Cell Division, Cell Diversity and Cellular Organisation

Context and exemplification

Assessable learning outcomes

During the cell cycle, genetic information is copied and passed to daughter cells. Microscopes can be used to view the different stages of the cycle.

In multicellular organisms, stem cells are modified to produce many different types of specialised cell. Understanding how stems cells can be modified has huge potential in medicine.

To understand how a whole organism functions, it is essential to understand the importance of cooperation between cells, tissues, organs and organ systems.

Candidates should be able to:

(a)

state that mitosis occupies only a small percentage of the cell cycle and that the remaining percentage includes the copying and checking of genetic information;

(b)

describe, with the aid of diagrams and photographs, the main stages of mitosis (behaviour of the chromosomes, nuclear envelope, cell membrane and centrioles);

(c)

explain the meaning of the term homologous pair of chromosomes;

(d)

explain the significance of mitosis for growth, repair and asexual reproduction in plants and animals;

(e)

outline, with the aid of diagrams and photographs, the process of cell division by budding in yeast;

(f)

state that cells produced as a result of meiosis are not genetically identical (details of meiosis are not required);

(g)

define the term stem cell;

(h)

define the term differentiation, with reference to the production of erythrocytes (red blood cells) and neutrophils derived from stem cells in bone marrow, and the production of xylem vessels and phloem sieve tubes from cambium;

(i)

describe and explain, with the aid of diagrams and photographs, how cells of multicellular organisms are specialised for particular functions, with reference to erythrocytes (red blood cells), neutrophils, epithelial cells, sperm cells, palisade cells, root hair cells and guard cells;

(j)

explain the meaning of the terms tissue, organ and organ system;

(k)

explain, with the aid of diagrams and photographs, how cells are organised into tissues, using squamous and ciliated epithelia, xylem and phloem as examples;

(l)

discuss the importance of cooperation between cells, tissues, organs and organ systems (HSW4).

10 © OCR 2008

GCE Biology v2

Practical Skills (HSW5) are assessed using specific OCR-set experiments. The practical work outlined below may be carried out as part of skill development.

Collection of quantitative data:

Make serial dilutions;

Measure the effect of solutions of different water potentials on plant tissues;

Use a colorimeter to investigate the effect of temperature on membrane permeability.

Collection and presentation of qualitative (descriptive) data:

Produce a root tip squash;

Use a light microscope to produce annotated drawings of the stages of mitosis.

Presentation, analysis and evaluation of quantitative data:

Calculate rates of diffusion rates;

Plot graphs of rate against temperature or mean change in mass against concentration.

Evaluation of data collection strategies:

Identify limitations in measuring change in mass in osmosis investigations.

© OCR 2008 11

GCE Biology v2

Module 2: Exchange and Transport

In order to survive, living cells need a supply of oxygen and nutrients. In single cells and small organisms these materials can enter by passive processes. However, once an organism reaches a critical size it requires specialised exchange surfaces and transport systems.

Links GCSE Criteria for Science: 3.7(i) (a), (d); 3.9(i) (a)

1.2.1 Exchange Surfaces and Breathing

Context and exemplification

Assessable learning outcomes

The gas exchange surface in the lungs is used

to exemplify the properties and functions of exchange surfaces in living things.

Candidates should be able to:

(a)

explain, in terms of surface area:volume ratio, why multicellular organisms need specialised exchange surfaces and single-celled organisms do not (HSW1);

(b)

describe the features of an efficient exchange surface, with reference to diffusion of oxygen and carbon dioxide across an alveolus;

(c)

describe the features of the mammalian lung that adapt it to efficient gaseous exchange;

(d)

describe, with the aid of diagrams and photographs, the distribution of cartilage, ciliated epithelium, goblet cells, smooth muscle and elastic fibres in the trachea, bronchi, bronchioles and alveoli of the mammalian gaseous exchange system;

(e)

describe the functions of cartilage, cilia, goblet cells, smooth muscle and elastic fibres in the mammalian gaseous exchange system;

(f)

outline the mechanism of breathing (inspiration and expiration) in mammals, with reference to the function of the rib cage, intercostal muscles and diaphragm;

(g)

explain the meanings of the terms tidal volume and vital capacity;

(h)

describe how a spirometer can be used to measure vital capacity, tidal volume, breathing rate and oxygen uptake;

(i)

analyse and interpret data from a spirometer.

1.2.2 Transport in Animals

Context and exemplification

Assessable learning outcomes

As animals become larger and more active, transport systems become essential to supply nutrients to and remove waste from individual

Candidates should be able to:

(a)

explain the need for transport systems in multicellular animals in terms of size, level of activity and surface area:volume ratio;

12 © OCR 2008

GCE Biology v2

cells.

Controlling supply of nutrients and removal of waste requires the co-ordinated activity of the heart and circulatory system.

(b)

explain the meaning of the terms single circulatory system and double circulatory system, with reference to the circulatory systems of fish and mammals;

(c)

explain the meaning of the terms open circulatory system and closed circulatory system, with reference to the circulatory systems of insects and fish;

(d)

describe, with the aid of diagrams and photographs, the external and internal structure of the mammalian heart;

(e)

explain, with the aid of diagrams, the differences in the thickness of the walls of the different chambers of the heart in terms of their functions;

(f)

describe the cardiac cycle, with reference to the action of the valves in the heart;

(g)

describe how heart action is coordinated with reference to the sinoatrial node (SAN), the atrioventricular node (AVN) and the Purkyne tissue;

(h)

interpret and explain electrocardiogram (ECG) traces, with reference to normal and abnormal heart activity;

(i)

describe, with the aid of diagrams and photographs, the structures and functions of arteries, veins and capillaries;

(j)

explain the differences between blood, tissue fluid and lymph;

(k)

describe how tissue fluid is formed from plasma;

(l)

describe the role of haemoglobin in carrying oxygen and carbon dioxide;

(m)

describe and explain the significance of the dissociation curves of adult oxyhaemoglobin at different carbon dioxide levels (the Bohr effect);

(n)

explain the significance of the different affinities of fetal haemoglobin and adult haemoglobin for oxygen.

1.2.3 Transport in Plants

Context and exemplification

Assessable learning outcomes

As plants become larger and more complex, transport systems become essential to supply nutrients to and remove waste from individual cells.

The supply of nutrients from the soil relies upon the flow of water through a vascular system, as does the movement of the products of photosynthesis.

Candidates should be able to:

(a)

explain the need for transport systems in multicellular plants in terms of size and surface area:volume ratio;

(b)

describe, with the aid of diagrams and photographs, the distribution of xylem and phloem tissue in roots, stems and leaves of dicotyledonous plants;

© OCR 2008 13

GCE Biology v2

(c)

describe, with the aid of diagrams and photographs, the structure and function of xylem vessels, sieve tube elements and companion cells;

(d)

define the term transpiration;

(e)

explain why transpiration is a consequence of gaseous exchange;

(f)

describe the factors that affect transpiration rate;

(g)

describe, with the aid of diagrams, how a potometer is used to estimate transpiration rates (HSW3);

(h)

explain, in terms of water potential, the movement of water between plant cells, and between plant cells and their environment. (No calculations involving water potential will be set);

(i)

describe, with the aid of diagrams, the pathway by which water is transported from the root cortex to the air surrounding the leaves, with reference to the Casparian strip, apoplast pathway, symplast pathway, xylem and the stomata;

(j)

explain the mechanism by which water is transported from the root cortex to the air surrounding the leaves, with reference to adhesion, cohesion and the transpiration stream;

(k)

describe, with the aid of diagrams and photographs, how the leaves of some xerophytes are adapted to reduce water loss by transpiration;

(l)

explain translocation as an energy-requiring process transporting assimilates, especially sucrose, between sources (eg leaves) and sinks (eg roots, meristem);

(m)

describe, with the aid of diagrams, the mechanism of transport in phloem involving active loading at the source and removal at the sink, and the evidence for and against this mechanism (HSW1, 7a).

Practical Skills (HSW5) are assessed using specific OCR-set experiments. The practical work outlined below may be carried out as part of skill development.

Collection of quantitative data:

Investigate surface area to volume relationships using agar blocks and dye;

Make measurements using a spirometer;

Use a potometer to compare xerophytes and non-xerophytes;

Use a potometer to investigate the effects of environmental factors on water uptake.

Collection and presentation of qualitative (descriptive) data:

Make measurements and annotated drawings during a heart dissection;

14 © OCR 2008

GCE Biology v2

Use a light microscope to make annotated drawings of lung tissue;

Use a light microscope to make annotated drawings of blood vessels.

Presentation, analysis and evaluation of quantitative data:

Calculate water uptake rates.

Evaluation of data collection strategies:

Identify the limitations of using a potometer.

1 of 1

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »