Biology b1 notes for aqa

The sugar can be used to provide energy. Carbon dioxide is absorbed from the air through the stomata pores in the leaf. In land plants water is absorbed from the soil by the roots and carried in the water vessels of the veins. An ECG is usually performed on a patient at rest. When the wave of depolarisation reaches the atroventricular node AVNit is delayed by 0.

In a positive feedback system, effectors increase the effect which triggered the response. If it gets too cold, the rate of photosynthesis will decrease. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide.

Responding to exercise As the atria fill with blood at the start of the cardiac cycle, stretch receptors in the muscle walls of the heart send nerve impulses to the cardiovascular control centre. It is specific and made of specialised tissue called cardiac muscle.

Negative feedback systems provide a way of maintaining a condition — a change is registered by receptors and effectors are stimulated to restore the equilibrium.

1) Photosynthesis

Rhythmic contraction of the cardiac muscle is coordinated through electrical impulses passing through the cardiac tissue.

When the baroreceptors do not stimulate the cardiovascular control centre it sends signals along the sympathetic nerve to stimulate the heart rate and increase blood pressure.

Different substances are built up synthesised from the sugar molecules and other molecules produced in photosynthesis, eg. The core body temperature must be maintained in a narrow range at around 37oC for cells to function and stop enzymes becoming denatured. They send nerve impulses to the parasympathetic system to slow the heart rate and cause vasodilation.

Blood is squeezed into the aorta and pulmonary artery. This maximises blood flow to the active muscles. A larger heart usually has a lower resting heart rate — it expels more blood with one beat so does not need to beat as frequently to keep blood circulation constant.

Increasing the light intensity will boost the rate of photosynthesis. Differences in resting heart rate are caused by different size, body size and genetic factors. This lowers the blood pressure.

It is oxidised by respiration to CO2 and H2O, and the energy released is used to drive other chemical reactions such as the building up of proteins. In contrast nerve impulses in the parasympathetic nerve inhibit the SAN and slow the heart down.

This increases the frequency of the signals from the pacemaker region so the heart rate increases. This sends a message to an effector which reverses or increases the change. The increased stretching of the heart atrial muscle also makes the muscles contract harder, increasing the volume of blood expelled at each stroke.

In the right atrium wall, muscle tissue is present called the sinoatrial node SAN which acts as a pacemaker. Atrial fibrillation — chest pains, fainting and increased risk of stroke. Homeostasis involves coordination and control. Increase in carbon dioxide. Increased heart rate caused by:) Photosynthesis Photosynthesis: is the process by which plants manufacture carbohydrates from raw materials using energy from light.

light energy is absorbed by chlorophyll – a green substance found in chloroplasts in green plant cells and algae absorbed light energy is used to convert carbon dioxide (from the air) and water (from. Here are all the GCSE past papers sorted by subjects that we have available for download.

3 The heart, energy and exercise

The GCSE papers categories are displayed below. After you click on. Powerpoint, cut and stick worksheet and exam question used for teaching new AQA GCSE Biology B1 to a Foundation level Y10 group.

Cut and stick could just be put in number order to save time!. GCSE Science Revision: GCSE Videos These videos cover the older outgoing GCSE Science spec which has final exams in These videos are aimed at the AQA spec but there is a lot of cross-over with other exam boards such as Edexcel.

GCSE BIOLOGY course help links. and for Combined Science Biology too. REVISION SUMMARY LINKS for GCSE Biology courses. Specification syllabus HELP pages - with links to all biology sections for the GCSE combined science, and separate GCSE biology courses.

General CELL BIOLOGY revision notes index. Introduction to plant and animal cell structure and function gcse biology revision notes. Introduction to cell specialisation gcse biology revision notes.

Microscopy - the development and use of microscopes in biology gcse biology revision notes. Diffusion, osmosis, active transport, exchange .

Biology b1 notes for aqa
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