This page contains the AQA GCSE Biology B16 Biology Hormonal Coordination Questions and kerboodle answers for revision and understanding . This page also contains the link to the notes and video for the revision of this topic.
Banner 1 B16.1 The Importance Of Communities AQA GCSE BIOLOGY B16 Biology Hormonal Coordination Kerboodle Answers: Page no. 259
1 a A community is made up of the populations of different species of animals and plants, protista, fungi, bacteria, and archaea that are all interdependent in a habitat.
b An ecosystem is different from a community as ecosystem is a collection of communities, but community is a collection of populations.
• Ecosystems could be either manmade or natural, but communities are always natural; or at least, communities are mended naturally inside a manmade ecosystem.
• Ecosystem is larger in all parameters than the community is.
• Community is not defined with particular characteristics, whereas a particular ecosystem is defined for its characteristics based on environmental and biological parameters.
• Communities are subjected to change with the affecting conditions, but a particular ecosystem does not change with those factors as it becomes another ecosystem with varying conditions.
• Ecosystem is always a saturated system but not the community.
2 Five examples of how animals and plants can interact in an ecosystem
The different animals and plants in an ecosystem are often interdependent:
• plants produce food by photosynthesis
• animals eat plants
• animals pollinate plants
• animals eat other animals
• animals use plant and animal materials to build nests and shelters
• plants need the nutrients from animal droppings and decay.
3 In stable environments, the species of living organisms may also be in balance. The number of species remains relatively constant, as does the population sizes of the different species, although they will vary slightly. These stable communities are very important. Examples include tropical rainforests, ancient oak woodlands, and mature coral reefs. These communities include a wide range of species – a single mature oak tree can house up to 1000 other species. Within limits, change can be tolerated and absorbed. For example, a falling tree allows light into the forest floor, so new seedlings can grow up. But when a large, stable community is lost, it cannot easily be replaced.
Banner 2 B16.2 Organisms in Their Environment AQA GCSE BIOLOGY B16 Biology Hormonal Coordination Kerboodle Answers : Page no. 261
1 The abiotic factors most likely to affect living organisms are
• Light intensity: light limits photosynthesis, so light intensity also affects the distribution of plants and animals.
• Temperature; temperature is a limiting factor on photosynthesis and therefore growth in plants.
• Moisture levels: if there is no water, there will be little or no life.
• Soil pH and mineral content the level of mineral ions, for example, nitrate ions, has a considerable impact on the distribution of plants.
• Wind intensity and direction: in areas with strong prevailing winds, the shape of the trees and the whole landscape is affected by the wind. It also means that plants transpire fast.
• Availability of oxygen: the availability of oxygen has a huge impact on water-living organisms. Some invertebrates can survive in water with very low oxygen levels.
• Availability of carbon dioxide: the level of carbon dioxide acts as a limiting factor for photosynthesis and plant growth. It can also affect the distribution of organisms.
2 Carnivorous plants such as sundews thrive where nitrate levels are very low because they can trap and digest animal prey. The nitrates they need are provided when they break down the animal protein, Most other plants struggle to grow in areas with low levels of mineral ions. The pH of the soil also has a major effect on what can grow in it and on the rate of decay and therefore on the release of mineral ions back into the soil. A low (acidic) pH inhibits decay.
3 a Light intensity is a non-living factor that affects the distribution of living organisms. Temperature is also a limiting factor on photosynthesis and therefore growth in plants.
b Factors affect the distribution of living organisms are
• Light intensity: light limits photosynthesis, so light intensity also affects the distribution of plants and animals. Some plants are adapted to living in low light levels, for example, they may have more chlorophyll or bigger leaves. Nettles growing in the shade of other bushes have leaves with a much bigger surface area than nettles growing in the open. However, most plants need plenty of light to grow well. The breeding cycles of many animal and plant species are linked to day length and light inrensic.
• Temperature; temperature is a limiting factor on photosynthesis and therefore growth in plants. In cold climates, temperature is always limiting. For example, the low Arctic temperatures mean the plants are all small. This in turn affects the numbers of herbivores that can survive and so the number of carnivores in the community.
4 A new predator can change the balance of organisms in a community, and ultimately the balance of living organisms in an entire habitat as the most important point being that the natural balance in an ecosystem is maintained. This balance may be disturbed due to the introduction of new species. As the predator population increases, the prey population decreases.
Banner 3 B16.3 Distribution and Abundance AQA GCSE BIOLOGY B16 Biology Hormonal Coordination Kerboodle Answers : Page no. 263
1 a Quadrats are used to investigate the size of a population of plants. They can also be used for animals that move very slowly, such as snails or sea anemones.
b It is important for samples to be random as Sample size is very important. You must choose your sample areas at random. This ensures that your results reflect the true distribution of the organisms and that any conclusions you make will be valid. There are a number of ways to make sure that the samples you take are random.
c In a series of 10 random 1 m2 quadrats, a class found the following numbers of dandelions: 6,3, 7,8,4,6,5, 7,9,8 for the mean, add all the readings together and divide by 10 (the number of readings):
6+3+7+8+4+6+5+7+9+8÷10 = 63÷10 = 6.3 dandelions per m2 on the school field
The median is the middle value when the numbers are put in order – in this case, the median is 6.5 dandelions per m2.
The mode is the most frequently occurring value – in this case, 6 dandelions per m2 .
3.Transects and quadrats are two ecological tools that allow us to quantify the relative abundance of organisms in an area.
Transect Sampling (using a single line) and Quadrat Sampling (counted within a grid).
A transect is simply a line we stretch over an area we want to study. The line must have regular measurements marked off, like a tape measure, & is held straight & stationary.
These sampling methods provide more accurate data than random sampling or simply guessing, but they take less time than counting every specimen in a certain area. Sampling helps us estimate & compare.
Banner 4 B16.4 Competition in Animals AQA GCSE BIOLOGY B16 Biology Hormonal Coordination Kerboodle Answers : Page no. 265
1 Animals that rely on a single type of food can easily become extinct because Many different species of herbivores eat the same plants. The animals that eat a wide range of plants are most likely to be successful. If a animal rely on a single type of food, the animal risk dying out and becoming extinct if anything happens to the only food source.
2 Two ways in which animals compete for mates in some species – such as deer, lions, and elephant seals – the males fight between themselves. The winner then gets to mate with several females.
Male peacocks display extravagant tail feathers to warn off other males and attract females.
Male lizards often display bright colours too.
3 b An obvious adaptation for grass and leaf eaters would involve their teeth. Herbivores do not need to catch or kill their food since they usually eat grass and leaves. So their teeth are not designed to tear flesh apart, instead they are designed for cutting and grinding tough plant material such as grass, leaves and bark.
Herbivores like horses and cows have sharp straight-edged teeth called incisors at the front of their mouths that they use to cut or bite off the tough grasses they eat. Wikipedia Commons
Herbivores also have flat teeth at the back of their skull called molars to grind tough plant material. gibbon skull
zebra skull molars incisors Herbivores typically have teeth similar to those shown in this zebra skull.
Rodents such as beavers, mice and rats are herbivores. They have incisor teeth used to gnaw. These teeth continue to grow throughout their lives as they wear down over time.
C Camouflage is an adaptation in which a species evolves to resemble its background. It is the technique used by many animals of resembling and blending in with their surroundings. It is a kind of colouring, body shape, and/or behaviour which animals use to confuse, distract, startle, or hide. It is used by both sides in the battle for survival. Prey animals use camouflage to remain undetected by their predators; predators use camouflage to sneak up, unseen, by their prey.
Chemical Defence: Some animals and insects use chemical defence. When attacked, some may spit, spray, or squirt chemicals which can cause pain or discomfort to the predator. Many snakes have venom, which when injected into the skin, can stun, numb, or paralyse the attacker. Skunks use an odour to protect themselves. They produce a strong liquid called musk. Musk is made and stored in glands near the tail. When another animal comes too close, the skunk raises its tail and sprays musk from its glands. While the intruder is reeling from the powerful odour, the skunk runs away.
d Giraaffe is an animal that feeds on the tender leaves at the top of trees.
Banner 5 B16.5 Competition in Plants AQA GCSE BIOLOGY B16 Biology Hormonal Coordination Kerboodle Answers : Page no. 267
1 Three ways in which plants overcome the problems of growing in the shade of another plant. One adaptation is breaking up the leaf into a series of narrow strips as palms, cycads and ferns demonstrate. The angle of the sun shifts during the day, and leaves arranged such that there are gaps between the veins allows light to pass through to lower leaves as well. In this way, the plant can grow many large leaves without the upper ones shading the lower ones.
Most plants which grow in shade are also small. Small plants require less energy than large ones. One unusual strategy some shade plants employ is to rely on something other than photosynthesis to provide the plant nutrients. Some live like fungus and absorb decomposing organic material.
The north American “Indian Pipe” plant grows underground most of the time and only emerges above ground to flower. All parts of the plant are either cream white or pink, since there is absolutely no chlorophyll. The other stragety is to become paracific on another plant. These sorts of plants also only emerge above ground to flower. A south asian species has one of the largest single flowers in the world.
The most common strategy when dealing with larger plants is to develop long stems and use the taller plants as a means of climbing up to more sunlight. Vines like ivy employ this stragety. Plants such as these have special roots which attach themselves to bark, but don’t draw any nutrients from their support. The “strangler fig” not only uses a tree as a climbing mechanism, but competes with and eventually kills its host. The roots of the fig completely cover the host’s trunk and prevent the tree from growing. The host eventually rots away, leaving a hollow, cylindrical shell made up of the fig’s roots.
b Snowdrops and bluebells grow and flower successfully in spite of living under large trees in woodlands because bluebells and snowdrops are well adapted to life in woodlands. In the spring they flower before the surrounding trees come out in full leaf. This means that they complete their life cycle while light levels are high. Bluebells are able to grow quickly in the spring because they have an energy store in the form of a bulb.
2 Many plants have adaptations to make sure that their seeds are spread successfully because the small plants need adaptations to help them survive. When a plant sheds its seeds they might land nearby. In this case, the parent plant will be in direct competition with its own seedlings. As the parent plant is large and settled, it will take most of the water, mineral ions, and light. So the plant will deprive its own offspring of everything they need to grow successfully. The roots of some desert plants even produce a chemical that stops seeds from germinating, killing the competition before it even begins to grow!
b Three successful adaptations for spreading seeds :Plants need help to pollinate and spread their seeds. Some plants – about 10% – use the wind for pollination– from the mightiest redwood to the smallest blade of grass. Yet most plants the help of animals to get the job done.
3 The dandelion produces seeds mainly in spring but continues through summer and autumn. The bitter leaves mean that not many animals eat it, so one flower can survive for many years. Dandelions are also adapted to being disturbed, so being moved doesn’t limit their ability to grow. The deep, twisted, brittle root makes it difficult to remove entirely so unless you remove it entirely it will just regrow. The dandelion has a rosette of leaves at its base to help it compete with the surrounding grass. They can grow almost anywhere because of their resilience, and their small parachute like seeds, mean that they can be blown many miles from their mother plant. Dandelions also don’t mind being trampled on meaning that they can survive where people walk often.
Baneer 6 B16.6 Adapt and Survive AQA GCSE BIOLOGY B16 Biology Hormonal Coordination Kerboodle Answers : Page no. 269
1 a Extremophiles (which loosely translates to ‘lovers of extremes’) are adapted to what is considered on Earth to be an extreme environment. From Antarctic ice to hydrothermal vents, extremophiles can be adapted to live in extreme cold, intense heat, harsh acidity, high saltiness, and a host of other conditions in which we humans have been surprised to detect life at all.
b Adaptations found in different extremophiles :Some extremophiles live at very high temperatures. Bacteria known as thermophiles can survive at temperatures ofover45°C and often up to 80 °C or higher. These extremephiles have specially adapted enzymes that do not denature at these high temperatures (Figure 3).
In fact, many themophiles cannot survive and reproduce at lower temperatures. Other bacteria and archaes live at very low temperatures, down to-15°C. They are found in ice packs and glaciers around the world. Most living organisms struggle to survive in a very salty environment because of the problems it causes with water balance. However, there are species of extremophile bacteria that can only live in extremely salty environments, such as the Dead Sea and salt flats. These bacteria have adaptations to their cytoplasm so that water does not move out of their cells into their salty environment by osmosis. However, in ordinary sea water they would swell up and burst! Not all extremophiles are microorganisms. Other species including specialised worms and fish have adaptations for survival in extreme conditions.
2 a Plants need light, carbon dioxide, water, oxygen, and mineral ions to produce glucose to give them the energy they need to survive.
b Animals need food from other living organisms, water, and oxygen
3 aThe special characteristics that enable plants and animals to be successful in a particular environment are called adaptations.
b Examples of adaptations in either animals or plants to a particular environment or way of life :Some sea birds get rid of all the extra salt they take in from the sea water by’ crying’ very salty tears from a special salt gland. Plants such as mangroves get rid of excess salt in a similar way.
• Animals and plants that survive extreme winter temperatures often produce a chemical in their cells that acts as an antifreeze. It stops the water in the cells from freezing and destroying the cell.
• Plants such as water lilies have lots of big air spaces in their leaves. They float on top of the water to photosynthesize.
Banner 7 B16.7 Adaptation in Animals AQA GCSE BIOLOGY B16 Biology Hormonal Coordination Kerboodle Answers : Page no. 271
1 The problems faced by animals that live in cold conditions:
i. They need layers of insulation to protect them from the cold environment
ii. They may have to travel for miles before finding a good source of prey/vegetation
iii. They need to stop their body temperature dropping
iv. You would have to be white to be camouflaged
v. Wind conditions (bad)
b The main problems faced by animals living in the desert are :
i. Coping with a lack of water in a dry environment
ii. Stopping your body temperature from getting to high
2 The surface area to volume ratio is very important when you look at the adaptations of animals that live in cold climates. The smaller the surface area to volume ratio the easier it is to reduce the transfer of energy to the environment and minimise cooling. This explains why so many Arctic mammals, such as seals, walruses, whales, and polar bears, are relatively large.
The surface area of the thin-skinned areas of their bodies, such as their ears, is often small, reducing cooling through energy transfers to the environment.
Many mammals in cold environments have plenty of insulation. Inside they have blubber, a thick layer of fat that builds up under the skin. On the outside they have a thick fur coat providing very effective insulation,
These adaptations reduce cooling by minimising energy transfers to the surroundings from the skin.
3 Visible adaptations of an elephant that enable it to keep cool in hot conditions are
Ears
An elephant’s primary cooling system is a pair of conspicuous ears that account for one-sixth of the animal’s body size. The African savanna species can reach heights of up to 13 feet at the shoulder, which makes for very large ears. By merely flapping their ears, elephants can reduce their body temperature by 10 degrees Fahrenheit or more. Air permeates the thin skin of the elephant’s ears, thereby cooling blood as it passes though a web of vessels inside the ears before returning to the body.
Skin
The wrinkles in an elephant’s mostly hairless skin help keep the animal cool by giving heat a larger surface area through which it can be dispelled. The creases and pleats in the hide of an elephant also trap and retain moisture longer than would smooth skin and prolong the evaporation process, allowing the animal to release up to 75 percent of her body heat.
Bathing
When the daytime heat gets to be too much, elephants enjoy submerging their bodies in water, as well as showering, which entails sucking water with their versatile, muscular trunks and then spraying themselves. In addition to helping elephants rid their thick skin of parasites, bathing is also an effective way for these enormous animals to reduce their body temperature.
Other Adaptations
Elephants are largely crepuscular, meaning they are most active at dawn and at twilight, when the sun is lower in the sky and temperatures are cooler. Moreover, using his trunk, which functions as a nose, in conjunction with a special gland known as the Jacobson’s organ that is attached to the roof of the mouth, an elephant can detect water sources up to 12 miles away. This ability is especially crucial in the dry season.
b Ways in which animals might be adapted to survive in hot, dry conditions :
Many desert animals have functional adaptations in their kidneys so they can produce very concentrated urine and need little or nothing to drink, They get the water they need from the food they eat. Animals that live in hot conditions often adapt their behaviour to keep cool. They are often most active in the early morning and evening, when it is cooler. During the cold nights and the hottest times of the day, they rest in burrows or shady areas. Many desert animals are relatively small, with relatively large surface area to volume ratios. They often have large, thin ears, to help them transfer energy to the surroundings through their skin, cooling them down.
c Adaptations which enable marine mammals, such as whales and seals, to survive are
Swimming Adaptations
Drag is reduced by hydrodynamic body forms.
Appendages are modified for maximal propulsion and minimal drag.
Thermoregulation
A large body with small surface-to-volume ratio reduces heat loss. Blubber or thick underfur is used as insulation.
Complex circulatory system in extremities is used to conserve and dissipate heat.
Young pinnipeds and cetaceans grow fast on milk with 40–50% fat (human milk is 3.3% fat).
Water Conservation
Most marine mammals rarely drink fresh water; instead, they:
Utilize water present in their food, inspired air, and blubber.
Have specialized kidneys that produce urine that is saltier than seawater.
Sensory Adaptations
Marine mammals communicate underwater with sound, and many species use sound (echolocation) to locate prey. Tactile senses are acute. Pinnipeds and fissipeds have well-developed facial whiskers.
Banner 8 : Page no. 273
1 a Plants need water for photosynthesis and to keep their tissues supported. If a plant does not get the water it needs, it wilts and eventually dies.
b Plants take in water from the soil through their roots. It moves up through the plant and into the leaves. There are small openings called stomata in the leaves of a plant. These open to allow gases in and out for photosynthesis and respiration. At the same time, water vapour is lost through the stomata by diffusion after it evaporates from the surface of the cells into the air spaces in the leaves.
2 a The rate at which a plant loses water is linked to the conditions in which it grows. When a plant grows in hot and dry conditions, photosynthesis and respiration take place quickly and as a result, plants lose water vapour very quickly.
b Plants that live in very hot, dry conditions need special adaptations to survive. Most plants either reduce their surface area so they lose less water or store water in their tissues, and some plants do both.
3 a Plants living in dry conditions have adaptations to reduce water loss from their leaves as
• Marram grass grows on sand dunes. It has tightly curled leaves to reduce the surface area for water loss so it can survive the dry conditions.
• Butcher' broom lives in shady, dry conditions under woodland trees and in hedgerows. To reduce water loss its 'leaves' are really flattened leaf-like bits of stem. The flowers and berries grow straight out from these stems. Stems have far fewer stomata than true leaves, and so the butcher'broom loses very little water. This ensures that it can survive and reproduce in conditions where there is little competition from other species.
The best-known desert plants are the cacti. Their leaves have been reduced to spines with a very small surface area. This means that cacti only lose a tiny amount of water. Not only that, their sharp spines also discourage animals from eating them.
the mesquite tree has roots that grow as far as 50m down into the soil. Storing water Some plants cope with dry conditions by storing water in their tissues. When there is plenty of water after a period of rain, the plant stores it. Some plants use their fleshy leaves to store water, while other plants use their stems or roots.
b Adaptations seen in plants to help them survive in dry conditions are: Sun avoidance and tolerance; small leaves or no leaves at all to minimize water loss
• photosynthesis instead often in trunk
• leaves frequently modied to spines which aid in defense but also can reflect excess light
• “accordion trunk” to reduce sun exposure
• special CO2 capture mechanism (C4/CAM) to minimize water loss while absorbing CO2
• highly reflective cuticle to reflect excess light
• dense hair to generate isolating boundary layer
• extremely seasonal growth and reproduction
• long lived, must be able to skip years if seasons don’t allow
• succulence; storing of water in specialized tissues (fleshy leaves, trunks, underground etc)
• also extensive and deep root system
Summary questions: Page No. 274
1 a Community is the sum of populations of all the codependent different species living in a specific geographic area.
b i In an ancient oak woodland organisms are interdependent as snake eating mice, insects eating leaves of trees.
ii In a desert, there is scarcity of water, animals take water from plants, plants depend on insects for pollination.
iii In a pond, small fishes feeds on planktons and large fishes depend on smaller fishes..
c i Organisms of the same species might compete against each other for food, for mating and for area.
ii Organisms of the same species might compete against each other for food, for prey and for space.
2 a Availability of nesting sites or sheltered areas. Animals travel long distances for nesting. For example, olive ridley turtles travel thousands of kilometer in search for a nesting site.
b Availability of nutrients: Plants need nutrients from earth, they cannot grow where nutrients such as phosphate are low.
c Temperature: It limits photosynthesis, extreme temperatures inhibit photosynthesis. Plants in both poles limit the size of their leaves.
d Amount of light: Light acts as limiting factor in photosynthesis, limiting type of plant that can grow. Example- plentiful light in rainforest means plants grow very large; light also affects animal breeding cycles, for example, sheep become fertile in autumn as days shorten so they lamb in the spring as longer days stimulate grass growth.
3 a In avoiding biased results it is important that the quadrat samples are random.
b to ensure the quadrat samples are random, students can use random number generator, each person must hold quadrat, by closing eyes. Then the person will spin around ,subsequently open eyes and must walk 10 yards for dropping quadrat.
c I Mean is the sum of all the values then dividing them with the number of values.
ii the median is the middle value in a set of data
iii Most common value in data set is mode.
d Mean: 7 Median: 7 Mode: 9
e Results suggest that there are more worms in flowerbed than in area of grass.
4 a Some students carried out samples along a line transact of a rocky shore. Line transect is a line across a habitat made by stretching tape between two points
b Factors which might affect the distribution of organisms along this transect are: Amount of sunlight; Organisms distribution is affected by the amount of sunlight that a plant exposes. Amount of time shore exposed and not under water.
c We can measure the distribution of organisms changes along this transect by placing quadrat at even distances along the line and by counting the organisms that fall within it
d The distribution of organisms on a shore will differ from the distribution of organisms in a field. As conditions on the shore are more changing than field. Distribution of flora and fauna on field is more consistent.
5
a Animals such as amphibians and reptiles do not control their own body temperature internally. They absorb energy from their surroundings and cannot move until they are warm. There are no frogs or snakes in the Arctic because arctic temperatures too low.
b Adaptations to cope up with extreme conditions.
Extremes of temperature – use conduct and environment to regulate
Body temperature by hiding in burrows or basking in sunlight,
Absence of water – thick skin/scales to retain water and efficient excretory
c Most desert animals are quite small. These adaptation helps them survive in the harsh conditions because there will be large surface area to volume ratio and to keep cool. Leaves frequently modied to spines which aid in defense but also can reflect excess light
6 a Competition between animals of the same species is so much more intense than competition between different species because they are competing for exactly the same things
b Marking out and defending a territory help an animal to compete successfully. Protects sufficient food for the animal and its young, advertising territory reduces conflict with competitors
c There are advantages and disadvantages for males of having an elaborate courtship ritual and coloration compared with fighting over females. The main advantage is that there is No injury or death as fight can cause death. There are disadvantages also: Development of colouration of display uses up lots of body’s resources. There is a risk of predation in the course of display.
Practice questions: Page No. 275
01 Ecological terms are : Community – all the organisms that live in a habitat
Ecosystem – the interaction of a community with the non-living parts of their environment
Habitat – the place where an organism lives
Interdependence – how different species rely on each other for survival
02.1 The labeled features helps the gorse plant to survive are:
Flowers – attract insects to pollinate them
Sharp spines – so animals / herbivores do not eat the plant
Small leaves – reduce water loss
02.3 Bluebells are wild plants that do not compete well with other plants. Bluebells grow in woods. The leaves of bluebells appear early in February, Large, dark green leaves quickly grow. Bluebells flower in April and May, but the plants die back by July and become dormant until the next spring. The trees in the wood are in full leaf by July,
The habitat and life cycle of bluebells:
Habitat:
• grow where (most) other plants cannot survive
• due to low level of light below the trees
• therefore, no / little competition for bluebells
Life cycle:
• grow before leaves on trees appear
• so do not compete for light
• can photosynthesise
• to make food to use during dormancy
03.1 Things animals may compete for are
• food
• mates
• territory / space
03.2 The woolly mammoth was adapted to survive during the ice age because of following features:
• long / thick hair or wool (for) insulation
• small surface area : volume ratio (therefore) lose less energy
• small ears / tail (therefore) lose less energy
03.3 natural selection is the process by which evolution happens.
03.4 if some animals grew a long nose / acquired characteristic (during their lifetime)
their offspring would inherit / also have a long nose
04 There is a wide variety/ of life in the wood. The different organisms depend on each other for their survival. Interaction of various organisms:
• plants provide food for animals
• plants release oxygen
• for respiration of all organisms
• plants / trees provide shelter for animals
• insects pollinate plants
• animals disperse seeds
• microbes return nutrients to soil for plants
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References:
BBC Bitesize
AQA GCSE Science Kerboodle textbook
Wikipedia
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