Biology - 4BI1 PearsonEdexcel

Gas Exchange

Gbogbo ọrọ náà

Every cell in your body needs a steady supply of oxygen for aerobic respiration and must get rid of carbon dioxide waste. Plants face a similar challenge: their cells need CO₂ for photosynthesis and release O₂ as a by-product. Gas exchange is the process that moves these gases between an organism and its environment, and it depends entirely on diffusion.

In this lesson you will explore how the human lungs and the plant leaf are structured for efficient gas exchange, how the breathing mechanism ventilates the lungs, and why smoking damages the system. Edexcel tests gas exchange with diagram-labelling, data-response, and extended-writing questions across both papers.

Ebumnobi

Understand the role of diffusion in gas exchange
Understand gas exchange (of carbon dioxide and oxygen) in relation to respiration and photosynthesis
Understand how the structure of the leaf is adapted for gas exchange
Describe the role of stomata in gas exchange
Understand how respiration continues during the day and night, but that the net exchange of carbon dioxide and oxygen depends on the intensity of light
Investigate the effect of light on net gas exchange from a leaf, using hydrogen-carbonate indicator
Describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes
Understand the role of the intercostal muscles and the diaphragm in ventilation
Explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries
Understand the biological consequences of smoking in relation to the lungs and the circulatory system, including coronary heart disease
Investigate breathing in humans, including the release of carbon dioxide and the effect of exercise

Akọmọ Ojú-ẹkọ

You take roughly 20 000 breaths every day without thinking about it. Each one pulls fresh air into a pair of lungs whose internal surface area is larger than a badminton court. Meanwhile, a single leaf on a tree silently opens and closes thousands of microscopic pores to exchange the same two gases. The physics behind both is identical: diffusion down a concentration gradient, across a thin, moist surface.

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Ayẹwo Ẹkọ

Ekele diri gi maka imecha ihe karịrị na Gas Exchange. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

Which structure is the site of gas exchange in the lungs? A) Bronchus B) Trachea C) Alveolus D) Bronchiole Answer: C
During inhalation, what happens to the diaphragm? A) It relaxes and domes upward B) It contracts and flattens C) It stays still D) It moves to the left Answer: B
Which component of cigarette smoke reduces the oxygen-carrying capacity of the blood? A) Tar B) Nicotine C) Carbon monoxide D) Particulates Answer: C
At night, a plant's net gas exchange at the stomata is: A) CO2 taken in, O2 released B) O2 taken in, CO2 released C) No exchange occurs D) O2 and CO2 both released Answer: B
Which of these is NOT an adaptation of alveoli for gas exchange? A) Thick walls for protection B) Large surface area C) Rich blood supply D) Moist lining Answer: A